Method for thermal modulation of neural activity

ABSTRACT

Methods and related systems for modulating neural activity by blocking conduction in peripheral neural structures with thermal stimuli are disclosed. Methods and systems for reversing effects of thermal blocking stimuli and/or for producing substantially permanent conduction block are also disclosed.

CROSS-REFERENCE USE TO RELATED APPLICATIONS

The present application is related to and claims the benefit of the earliest available effective filing date(s) from the following listed application(s) (the “Related Applications”) (e.g., claims earliest available priority dates for other than provisional patent applications or claims benefits under 35 USC §119(e) for provisional patent applications, for any and all parent, grandparent, great-grandparent, etc. applications of the Related Application(s)).

RELATED APPLICATIONS

For purposes of the USPTO extra-statutory requirements, the present application constitutes a continuation-in-part of U.S. patent application Ser. No. 11/999,721, titled “METHOD AND SYSTEM FOR CYCLICAL NEURAL MODULATION BASED ON ACTIVITY STATE”, naming RALPH G. DACEY, JR., GREGORY J. DELLA ROCCA, COLIN P. DERDEYN, JOSHUA L. DOWLING, ELEANOR V. GOODALL, RODERICK A. HYDE, MURIEL Y. ISHIKAWA, JORDIN T. KARE, ERIC C. LEUTHARDT, NATHAN P. MYHRVOLD, MICHAEL A. SMITH, LOWELL L. WOOD, JR., VICTORIA Y. H. WOOD, AND GREGORY J. ZIPFEL as inventors, filed 5 Dec. 2007, which is currently co-pending, or is an application of which a currently co-pending application is entitled to the benefit of the filing date.

For purposes of the USPTO extra-statutory requirements, the present application constitutes a continuation-in-part of U.S. patent application Ser. No. 12/070,332, titled “METHOD FOR MAGNETIC MODULATION OF NEURAL CONDUCTION”, naming RALPH G. DACEY, JR., GREGORY J. DELLA ROCCA, COLIN P. DERDEYN, JOSHUA L. DOWLING, ELEANOR V. GOODALL, RODERICK A. HYDE, MURIEL Y. ISHIKAWA, JORDIN T. KARE, ERIC C. LEUTHARDT, NATHAN P. MYHRVOLD, MICHAEL A. SMITH, LOWELL L. WOOD, JR., VICTORIA Y. H. WOOD, AND GREGORY J. ZIPFEL as inventors, filed 15 Feb. 2008, which is currently co-pending, or is an application of which a currently co-pending application is entitled to the benefit of the filing date.

For purposes of the USPTO extra-statutory requirements, the present application constitutes a continuation-in-part of U.S. patent application Ser. No. 12/070,369, titled “SYSTEM FOR MAGNETIC MODULATION OF NEURAL CONDUCTION”, naming RALPH G. DACEY, JR., GREGORY J. DELLA ROCCA, COLIN P. DERDEYN, JOSHUA L. DOWLING, ELEANOR V. GOODALL, RODERICK A. HYDE, MURIEL Y. ISHIKAWA, JORDIN T. KARE, ERIC C. LEUTHARDT, NATHAN P. MYHRVOLD, MICHAEL A. SMITH, LOWELL L. WOOD, JR., VICTORIA Y. H. WOOD, AND GREGORY J. ZIPFEL as inventors, filed 15 Feb. 2008, which is currently co-pending, or is an application of which a currently co-pending application is entitled to the benefit of the filing date.

For purposes of the USPTO extra-statutory requirements, the present application constitutes a continuation-in-part of U.S. patent application Ser. No. 12/070,361, titled “METHOD FOR ELECTRICAL MODULATION OF NEURAL CONDUCTION”, naming RALPH G. DACEY, JR., GREGORY J. DELLA ROCCA, COLIN P. DERDEYN, JOSHUA L. DOWLING, ELEANOR V. GOODALL, RODERICK A. HYDE, MURIEL Y. ISHIKAWA, JORDIN T. KARE, ERIC C. LEUTHARDT, NATHAN P. MYHRVOLD, MICHAEL A. SMITH, LOWELL L. WOOD, JR., VICTORIA Y. H. WOOD, AND GREGORY J. ZIPFEL as inventors, filed 15 Feb. 2008, which is currently co-pending, or is an application of which a currently co-pending application is entitled to the benefit of the filing date.

For purposes of the USPTO extra-statutory requirements, the present application constitutes a continuation-in-part of U.S. patent application Ser. No. 12/070,331, titled “SYSTEM FOR ELECTRICAL MODULATION OF NEURAL CONDUCTION”, naming RALPH G. DACEY, JR., GREGORY J. DELLA ROCCA, COLIN P. DERDEYN, JOSHUA L. DOWLING, ELEANOR V. GOODALL, RODERICK A. HYDE, MURIEL Y. ISHIKAWA, JORDIN T. KARE, ERIC C. LEUTHARDT, NATHAN P. MYHRVOLD, MICHAEL A. SMITH, LOWELL L. WOOD, JR., VICTORIA Y. H. WOOD, AND GREGORY J. ZIPFEL as inventors, filed 15 Feb. 2008, which is currently co-pending, or is an application of which a currently co-pending application is entitled to the benefit of the filing date.

For purposes of the USPTO extra-statutory requirements, the present application constitutes a continuation-in-part of U.S. patent application Ser. No. ______, titled “SYSTEM FOR THERMAL MODULATION OF NEURAL CONDUCTION”, naming RALPH G. DACEY, JR., GREGORY J. DELLA ROCCA, COLIN P. DERDEYN, JOSHUA L. DOWLING, ELEANOR V. GOODALL, RODERICK A. HYDE, MURIEL Y. ISHIKAWA, JORDIN T. KARE, ERIC C. LEUTHARDT, NATHAN P. MYHRVOLD, MICHAEL A. SMITH, LOWELL L. WOOD, JR., VICTORIA Y. H. WOOD, AND GREGORY J. ZIPFEL as inventors, filed substantially contemporaneously herewith, which is currently co-pending, or is an application of which a currently co-pending application is entitled to the benefit of the filing date.

The United States Patent Office (USPTO) has published a notice to the effect that the USPTO's computer programs require that patent applicants reference both a serial number and indicate whether an application is a continuation or continuation-in-part. Stephen G. Kunin, Benefit of Prior-Filed Application, USPTO Official Gazette Mar. 18, 2003, available at http://www.uspto.jov/web/offices/com/sol/og/2003/week11/patbene.htm. The present Applicant Entity (hereinafter “Applicant”) has provided above a specific reference to the application(s)from which priority is being claimed as recited by statute. Applicant understands that the statute is unambiguous in its specific reference language and does not require either a serial number or any characterization, such as “continuation” or “continuation-in-part,” for claiming priority to U.S. patent applications. Notwithstanding the foregoing, Applicant understands that the USPTO's computer programs have certain data entry requirements, and hence Applicant is designating the present application as a continuation-in-part of its parent applications as set forth above, but expressly points out that such designations are not to be construed in any way as any type of commentary and/or admission as to whether or not the present application contains any new matter in addition to the matter of its parent application(s).

All subject matter of the Related Applications and of any and all parent, grandparent, great-grandparent, etc. applications of the Related Applications is incorporated herein by reference to the extent such subject matter is not inconsistent herewith.

SUMMARY

In one aspect, a method of modulating neural activity may include producing a reversible conduction block in a peripheral neural structure of a subject with a thermal stimulus while the subject is in a first activity state, reversing the reversible conduction block in the peripheral neural structure of the subject to permit conduction in the peripheral neural structure when the subject is in a second activity state, and repeating the steps of producing a reversible conduction block in a peripheral neural structure of a subject with a thermal stimulus while the subject is in a first activity state and reversing the reversible conduction block in the peripheral neural structure of the subject to permit conduction in the peripheral neural structure when the subject is in a second activity state.

In another aspect, a method of modulating neural activity may include producing a reversible conduction block in a peripheral neural structure of a subject with a thermal stimulus while the subject is in a first activity state, reversing the reversible conduction block in the peripheral neural structure of the subject to permit conduction in the peripheral neural structure when the subject is in a second activity state by applying a reversing stimulus configured to counter the blocking stimulus used to produce the reversible conduction block in the peripheral neural structure of the subject, and repeating the steps of producing a reversible conduction block in a peripheral neural structure of a subject while the subject is in a first activity state and reversing the reversible conduction block in the peripheral neural structure of the subject to permit conduction in the peripheral neural structure when the subject is in a second activity state.

In another aspect, a method of modulating neural activity may include producing a reversible conduction block in a peripheral neural structure of a subject with a thermal stimulus while the subject is in a first activity state, reversing the reversible conduction block in the peripheral neural structure of the subject to permit conduction in the peripheral neural structure when the subject is in a second activity state, repeating the steps of producing a reversible conduction block in a peripheral neural structure of a subject while the subject is in a first activity state and reversing the reversible conduction block in the peripheral neural structure of the subject to permit conduction in the peripheral neural structure when the subject is in a second activity state, determining that producing the reversible conduction block in the peripheral neural structure of the subject while the subject is in a first activity state results in a desired effect in the subject, and producing a non-reversible conduction block in the peripheral neural structure of the subject.

In still another aspect, a method of modulating neural activity may include producing a reversible conduction block of a subset of nerve fibers in a peripheral neural structure of a subject with a thermal stimulus while the subject is in a first activity state, reversing the reversible conduction block of the subset of nerve fibers in the peripheral neural structure of the subject to permit conduction in the subset of nerve fibers in the peripheral neural structure when the subject is in a second activity state, and repeating the steps of producing a reversible conduction block in the subset of nerve fibers in a peripheral neural structure of a subject while the subject is in a first activity state and reversing the reversible conduction block in the subset of nerve fibers in the peripheral neural structure of the subject to permit conduction in the subset of nerve fibers in the peripheral neural structure when the subject is in a second activity state.

In addition to the foregoing, other method aspects are as described in the claims, drawings, and text forming a part of the present disclosure.

In one aspect, a neural modulation system may include a signal input structure configured to receive a signal indicative of an activity state of at least a portion of a body of a subject innervated by a peripheral neural structure, a signal processing portion configured to distinguish a first activity state of the at least a portion of the body of the subject innervated by the peripheral neural structure from a second activity state of the at least a portion of the body of the subject innervated by the peripheral neural structure from the signal received at the signal input structure and generate a blocking stimulus control signal for driving production of a thermal blocking stimulus configured to reversibly block conduction in the peripheral neural structure of the subject during at least a portion of the first activity state, and a blocking stimulus source configured to produce a thermal blocking stimulus responsive to the blocking stimulus control signal.

In another aspect, a neural modulation system may include a signal input structure configured to receive a signal indicative of an activity state of at least a portion of a body of a subject innervated by a peripheral neural structure, a signal processing portion configured to distinguish a first activity state of the at least a portion of the body of the subject innervated by the peripheral neural structure from a second activity state of the at least a portion of the body of the subject innervated by the peripheral neural structure from the signal received at the signal input structure and generate a blocking stimulus control signal for driving production of a thermal blocking stimulus configured to reversibly block conduction in the peripheral neural structure of the subject during at least a portion of the first activity state, and a blocking stimulus source configured to be worn on the body of the subject and to produce a thermal blocking stimulus responsive to the blocking stimulus control signal.

In another aspect, a neural modulation system may include a signal input structure configured to receive a signal indicative of an activity state of at least a portion of a body of a subject innervated by a peripheral neural structure, a signal processing portion configured to distinguish a first activity state of the at least a portion of the body of the subject innervated by the peripheral neural structure from a second activity state of the at least a portion of the body of the subject innervated by the peripheral neural structure from the signal received at the signal input structure and generate a blocking stimulus control signal for driving production of a thermal blocking stimulus configured to reversibly block conduction in the peripheral neural structure of the subject during at least a portion of the first activity state, and a blocking stimulus source configured to be positioned beneath at least a portion of the body of the subject and to produce a thermal blocking stimulus responsive to the blocking stimulus control signal.

In yet another aspect, a neural modulation system may include a signal input structure configured to receive a signal indicative of an activity state of at least a portion of a body of a subject innervated by a peripheral neural structure, a signal processing portion configured to distinguish a first activity state of the at least a portion of the body of the subject innervated by the peripheral neural structure from a second activity state of the at least a portion of the body of the subject innervated by the peripheral neural structure from the signal received at the signal input structure and generate a blocking stimulus control signal for driving production of a thermal blocking stimulus configured to reversibly block conduction in the peripheral neural structure of the subject during at least a portion of the first activity state, and a blocking stimulus source configured to be implanted within the body of the subject and to produce a thermal blocking stimulus responsive to the blocking stimulus control signal.

In still another aspect, a neural modulation system may include a signal input structure configured to receive a signal indicative of an activity state of at least a portion of a body of a subject innervated by a peripheral neural structure; a signal processing portion configured to distinguish a first activity state of the at least a portion of the body of the subject innervated by the peripheral neural structure from a second activity state of the at least a portion of the body of the subject innervated by the peripheral neural structure from the signal received at the signal input structure, generate a blocking stimulus control signal for driving production of a thermal blocking stimulus configured to reversibly block conduction in the peripheral neural structure of the subject during at least a portion of the first activity state, and generate a reversing stimulus control signal for driving production of a reversing stimulus to counter the thermal blocking stimulus used to produce the reversible conduction block in the peripheral neural structure of the subject; a blocking stimulus source configured to produce a thermal blocking stimulus responsive to the blocking stimulus control signal; and a reversing stimulus source configured to produce a reversing stimulus responsive to the reversing stimulus control signal.

In a further aspect, a neural modulation system may include a signal input structure configured to receive a signal indicative of an activity state of at least a portion of a body of a subject innervated by a peripheral neural structure; a signal processing portion configured to distinguish a first activity state of the at least a portion of the body of the subject innervated by the peripheral neural structure from a second activity state of the at least a portion of the body of the subject innervated by the peripheral neural structure from the signal received at the signal input structure, generate a blocking stimulus control signal for driving production of a thermal blocking stimulus configured to reversibly block conduction in the peripheral neural structure of the subject during at least a portion of the first activity state, determine that producing the reversible conduction block in the peripheral neural structure of the subject while the subject is in a first activity state results in a desired effect in the subject, and generate a non-reversible blocking source control signal for driving a non-reversible blocking source to perform an action adapted for producing a non-reversible conduction block in the peripheral neural structure of the subject; a blocking stimulus source configured to produce a thermal blocking stimulus responsive to the blocking stimulus control signal; and a non-reversible blocking source configured to perform an action adapted for producing a non-reversible conduction block in the peripheral neural structure of the subject responsive to the non-reversible blocking source control signal.

In addition to the foregoing, other system aspects are described in the claims, drawings, and text forming a part of the present disclosure.

In one or more various aspects, related systems include but are not limited to circuitry and/or programming, including instructions carried on signal bearing media, for effecting the herein-referenced method aspects.

The foregoing is a summary and thus may contain simplifications, generalizations, inclusions, and/or omissions of detail; consequently, those skilled in the art will appreciate that the summary is illustrative only and is NOT intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1A is an illustration of conduction in a single nerve fiber;

FIG. 1B is an illustration of conduction block in the single nerve fiber depicted in FIG. 1A;

FIG. 2A is an illustration of conduction in nerve;

FIG. 2B is an illustration of the effect of a complete conduction block in the nerve depicted in FIG. 2A;

FIG. 2C is an illustration of the effect of a partial conduction block in the nerve depicted in FIG. 2A;

FIG. 3 is a schematic diagram of a system for producing conduction block in a peripheral neural structure;

FIG. 4 is a flow diagram of method of modulating neural activity;

FIG. 5 is an illustration of application patterns for blocking stimuli;

FIG. 6 is a flow diagram of method of modulating neural activity;

FIG. 7 is a flow diagram of method of modulating neural activity;

FIG. 8 is an illustration of an embodiment of a system in which a blocking stimulus source is located in an arm band;

FIG. 9 is an illustration of types of blocking stimuli;

FIG. 10 is an illustration of an embodiment of a system in which a blocking stimulus source is located in chair;

FIG. 11A is an illustration of an embodiment of a system in which a blocking stimulus source is located in a bed;

FIG. 11B is a close-up view of a portion of FIG. 11A;

FIG. 12 is an illustration of an embodiment of a system in which a blocking stimulus source is implanted within the body of a subject;

FIG. 13 is a flow diagram of a method of modulating neural activity;

FIG. 14 is a flow diagram of a method of modulating neural activity;

FIG. 15 is an illustration of an embodiment of a neural modulation system with a reversing stimulus source;

FIG. 16 is a flow diagram of a method of modulating neural activity;

FIG. 17 is a flow diagram of a method of modulating neural activity;

FIG. 18 is an illustration of an embodiment of a neural modulation system with a non-reversible blocking source;

FIG. 19 is a flow diagram of a method of modulating neural activity;

FIGS. 20A-20C depict examples of thermal blocking stimulus sources;

FIG. 21 is a block diagram of an example of a neural modulation system;

FIG. 22 is a block diagram of an example of a neural modulation system;

FIG. 23 is a block diagram of another example of a neural modulation system;

FIG. 24 is a block diagram of a further example of a neural modulation system;

FIG. 25 is a block diagram of a further example of a neural modulation system;

FIG. 26 is a block diagram of another example of a neural modulation system; and

FIG. 27 is a block diagram of a signal processing portion of a neural modulation system.

DETAILED DESCRIPTION

In the following detailed description, reference is made to the accompanying drawings, which form a part hereof. In the drawings, similar symbols typically identify similar components, unless context dictates otherwise. The illustrative embodiments described in the detailed description, drawings, and claims are not meant to be limiting. Other embodiments may be utilized, and other changes may be made, without departing from the spirit or scope of the subject matter presented here.

Although the following terms are known in the art, they are generally defined below for the convenience of the reader:

Definitions

Central Nervous System (CNS)—the brain, spinal cord, optic nerves and retina.

Peripheral Nervous System (PNS)—all the nerves in the body that lie outside of the brain and spinal cord, i.e., the cranial nerves, spinal nerves, nerve plexuses, and their associated spinal and autonomic ganglia.

Autonomic Nervous System (ANS)—the portion of the nervous system that regulates involuntary body functions, including heart and circulation, respiration, digestion, temperature regulation, etc. The Autonomic nervous system includes two divisions, the sympathetic nervous system and the parasympathetic nervous system.

Sympathetic nervous system—the division of the autonomic nervous system, which, broadly speaking, functions to mobilize the body's energy and resources during times of stress and arousal to prepare for “fight or flight”, e.g., it accelerates heart rate, constricts blood vessels, elevates blood pressure, etc.

Parasympathetic nervous system—the division of the autonomic nervous system that regulates body functions during relaxed states.

Neuron—a nerve cell, the basic functional unit of the nervous system. A neuron typically includes a cell body, and one or more processes called axons and dendrites.

Axon—An axon is a long slender process of a nerve cell that conducts electrical impulses away from the cell body.

Action Potential—a brief, regenerative change in membrane potential that propagates actively along membrane of neuron or other excitable cells.

Dendrite—A dendrite is a process of a nerve cell that conducts electrical impulses toward the cell body. Often, a neuron may have multiple, relatively short dendrites.

Nerve Fiber—The term “nerve fiber” may be used in connection with peripheral neurons to describe long slender processes (either axons or dendrites) that may conduct electrical impulses away from or toward the cell body.

Nerve—a cable-like bundle of multiple nerve fibers, capable of carrying signals between the central nervous system and other organs and tissues of the body. Cranial nerves may connect directly to parts of the brain.

Fascicle—a bundle of nerve fibers within a nerve. Each fascicle is surrounded by a dense sheath of tissue called perineurium, while a group of fascicles that make up a nerve are surrounded and held together by looser connective tissue called epineurium.

Nerve Plexus—a region of crossover and regrouping of nerve fibers from multiple nerves.

Ganglion—in the peripheral nervous system, a cluster of nerve cell bodies; sensory (afferent) ganglia lie along spinal column on the dorsal roots. Autonomic ganglia (containing the cell bodies of autonomic neurons) may lie parallel to the spinal column or in or near their target organs.

Spinal Root—root portion of spinal nerve, as it branches off of spinal cord and passes through bony canal through vertebra.

Methods and systems for modulating neural activity by producing conduction block in peripheral neural structures in a controlled fashion are disclosed herein. Effects of peripheral nerve block depend at least in part on the type of nerve or nerve fibers blocked and the target organ or tissue innervated by the blocked nerve or nerve fibers. It is believed that delivery of blocking stimuli to coincide at least in part with particular activity states in a subject may allow desired effects of blocking (e.g., modulation of immune or inflammatory response, decrease in pain, etc.) to be produced while limiting inconvenience, discomfort, and/or other undesired effects (numbness, diminished or altered sensation, decreased muscle force or control, interference with autonomic functions), or for other reasons. For example, blocking stimuli may be delivered during periods of reduced activity of the subject (including, but not limited to, physical activity, physiological activity, or other measures of activity, in all or a portion of the body of the subject). Effects of peripheral nerve block depend at least in part on the type of nerve or nerve fibers blocked and the target organ or tissue innervated by the blocked nerve or nerve fibers.

By way of background, FIG. 1A and 1B provide a conceptual illustration of the blocking of conduction of an action potential along a single nerve fiber. FIG. 1A depicts conduction of action potentials (referred to collectively as “neural activity”) in a single nerve fiber 10 (an elongated nerve process, or axon or dendrite) when no conduction block is present. Neural activity may be sensed from nerve fiber 10 with, for example, an electrode 12 located at a first position 14 on nerve fiber 10. Sensed neural activity may be represented by trace 16, which includes action potentials 18 a, 18 b, 18 c and 18 d occurring at times t_(a), t_(b), t_(c) and t_(d). The direction of conduction of action potentials along nerve fiber 10 is indicated by the arrow. Trace 20, which may be sensed with electrode 22 at a second position 24 located at a distance l from first position 14 on nerve fiber 10, includes action potentials 18 a, 18 b, 18 c and 18 d occurring at times t_(a)+t_(cd), t_(b)+t_(cd), t_(c)+t_(cd) and t_(d)+t_(cd), where t_(cd) is the conduction delay time, or the time for the action potentials to conduct down nerve fiber 10 from first position 14 to second position 24. Conduction delay time t_(cd) is equal to l/v, where l is the distance between first position 14 and second position 24 and v is the conduction velocity.

FIG. 1B depicts the effect of a conduction block in nerve fiber 10, indicated by cross-hatching in blocked region 30. When conduction is blocked at region 30, action potentials 28 e, 28 f, 28 g and 28 h, occurring at times t_(e), t_(f), t_(g) and t_(h) in trace 26 may be sensed with electrode 12 at first position 14. However, conduction of the action potentials in the direction indicated by the arrow is blocked so they cannot travel past region 30 to second position 24. Accordingly, trace 32, which may be sensed with electrode 22 at second position 24, will not contain any action potentials.

FIGS. 2A-2F illustrate the effects of complete and partial conduction block on a nerve made up of multiple nerve fibers. A nerve 50 is shown in longitudinal section in FIG. 2A, and in cross section (taken at section line 2B-2B) in FIG. 2B. Nerve 50 contains multiple nerve fibers 54. An electrode 56 at first position 58 may record a compound signal 60 from nerve 50. Compound signal 60 is made up of the summation of action potentials produced by multiple individual nerve fibers (e.g., as may be produced in response to an electrical stimulus or other stimulus that activates multiple nerve fibers at substantially the same time). If the direction of conduction is as indicated by the arrow, an electrode 62 at second position 64 may record compound signal 66. Because action potentials on individual nerve fibers may travel at different conduction velocities, action potentials that sum to form compound signal 60 at first position 58 may not arrive at second position 64 at the same delays relative to each other. Accordingly, compound signal 66 may represent the summation of the same action potentials that made up compound signal 60, but because they arrive at second position 64 at different relative delays, compound signal 66 may have a different shape than compound signal 60.

FIG. 2C depicts nerve 50 in longitudinal section, with a complete conduction block in region 70, as indicated by cross-hatching. Conduction block is indicated in region 74 in the cross-section of the same nerve, taken at section line 2D-2D and shown in FIG. 2D. Compound signal 75 sensed at first position 58 is unchanged relative to compound signal 60 shown in FIG. 1A, but compound signal 76, sensed at second position 64 with electrode 62, includes no activity, because conduction of action potentials was blocked in all fibers at the blocked region as indicated at 70 and 74.

FIG. 2E depicts in longitudinal view nerve 50 with a partial conduction block, with blocked fibers in area 80, as indicated by cross-hatching. Conduction block is indicated by cross-hatching in area 84 in the cross-section shown in FIG. 2F, taken along section line 2F-2F in FIG. 2E. Compound signal 85 sensed at first position 58 is unchanged relative to compound signal 60 as shown in FIG. 2A, but compound signal 86, sensed at second position 64 with electrode 62, is of lower amplitude because conduction of action potentials was blocked in the subset of fibers passing through the blocked region as indicated at areas 80 and 84. Accordingly, compound signal 86 is formed by the summation of action potentials from those fibers lying outside of area 80, i.e. fibers lying within region 88 in cross-section of FIG. 2F. As seen in the cross-section of FIG. 2F, when a partial conduction block is produced in a nerve, a subset of the nerve fibers (lying within area 84) may be blocked, and another subset of the nerve fibers (lying within region 88) may conduct as usual. In the example shown in FIG. 2F, the blocked subset of nerve fibers falls within a particular spatial distribution. In some cases, a subset of nerve fibers within a nerve may be blocked based on fiber diameter, fiber type, presence of a biomarker, or other parameter instead of or in addition to the location of the nerve fiber with the nerve.

Conduction block in peripheral nerves may be produced by application of appropriately configured thermal stimuli as described elsewhere herein, or by various other approaches as known to those of skill in the art. For example, commonly owned U.S. patent application Ser. No. 11/999,721, titled “METHOD AND SYSTEM FOR CYCLICAL NEURAL MODULATION BASED ON ACTIVITY” filed 5 Dec. 2007, and listing as inventors Ralph G. Dacey, Jr., Gregory J. Della Rocca, Colin P. Derdeyn, Joshua L. Dowling, Eleanor V. Goodall, Roderick A. Hyde, Muriel Y. Ishikawa, Jordin T. Kare, Eric C. Leuthardt, Nathan P. Myhrvold, Michael A. Smith, Lowell L. Wood, Jr., Victoria Y. H. Wood, Gregory J. Zipfel, which is incorporated herein by reference in its entirety, describes various approaches for blocking conduction in peripheral neural structures.

FIG. 3 is a schematic diagram illustrating a neural modulation system 100 for modulating neural activity by blocking conduction in at least a portion of a peripheral neural structure 140. A body portion of a subject is indicated generally at 120, including skin surface 130 overlying peripheral neural structure 140 (in this example, a peripheral nerve) and surrounding tissue 150. Neural modulation system 100 includes blocking stimulus source 160, which is capable of generating thermal blocking stimulus 170 to block conduction in region 180 of peripheral neural structure 140 (in this example, a peripheral nerve). The neural modulation system 100 includes a signal input structure 192 configured to receive a signal 194 indicative of an activity state of at least a portion 120 of a body of a subject innervated by a peripheral neural structure 140, a signal processing portion 110 configured to distinguish a first activity state of the at least a portion 120 of the body of the subject innervated by the peripheral neural structure 140 from a second activity state of the at least a portion 120 of the body of the subject innervated by the peripheral neural structure 140 from the signal 194 received at the signal input structure 192 and generate a blocking stimulus control signal 196 for driving production of a thermal blocking stimulus 170. Thermal blocking stimulus 170 may be configured to reversibly block conduction in the peripheral neural structure 140 of the subject during at least a portion of the first activity state; blocking stimulus source 160 may be configured to produce a thermal blocking stimulus responsive to the blocking stimulus control signal 196. Sensor 190 may sense at least one parameter indicative of an activity state in the subject, which may be an overall activity level of the subject, or a level of use or activity of a body portion innervated by peripheral neural structure 140. A signal 194 from sensor 190 may be connected to signal input structure 192 of signal processing portion 110.

The term “activity state” refers to one of at least two possible categories of activity that are characterized by and distinguishable from each other by one or more quantifiable parameters. Activity may refer to overall activity of the subject or use or activity of a body portion innervated by the peripheral neural structure. Activity may include or be reflected by physical activity, physiological activity, or other measures or indicators of activity, as described in greater detail elsewhere herein.

For purposes of methods as disclosed herein, at least two activity states may be defined, with appropriate values or value ranges of the one or more quantifiable parameters associated therewith. The different activity states may differ with regard to the level of activity, or, in some cases, the nature of the activity. In some cases, the overall activity of the subject may be lower in the first activity state than in the second activity state. For example, the first activity state may be a “sleep state” and the second activity state may be a “waking state.” Alternatively, the first activity state may be a “resting,” “lying down” or “sitting” activity state while the second activity state may be a “moving about,” “standing” or “walking” activity state.

The activity or use of a specific portion of the subject's body, rather than the overall activity of the subject, may be of interest. For example, the first and second activity states may be defined such that the use of a body portion innervated by the peripheral neural structure by the subject is lower in the first activity state than in the second activity state. If the body portion innervated by the peripheral neural structure is the subject's arm, a low use state may be obtained when the arm is resting in the subject's lap, on an arm rest or table top, or in a sling, while the subject stands or walks. Low use or activity of the subject's arm may also be obtained while the overall activity of the subject is low, e.g. the subject is lying down or sleeping. Conversely, a moderate or high use or activity state of a body portion, e.g., the subject's arm, may be obtained while the subject's overall activity level is either high or low. For example, the subject could use the arm for writing, typing, holding a book, knitting, etc. while sitting quietly with a low overall activity level. A subject may also have a high use or activity state of, e.g., an arm in combination with an overall high activity level.

FIG. 4 illustrates a method of modulating neural activity that may be carried out, for example, using the system depicted in FIG. 3. The method shown in FIG. 4 includes the steps of producing a reversible conduction block in a peripheral neural structure of a subject with a thermal stimulus while the subject is in a first activity state (step 200), reversing the reversible conduction block in the peripheral neural structure of the subject to permit conduction in the peripheral neural structure when the subject is in a second activity state (step 202), and repeating the steps of producing a reversible conduction block in a peripheral neural structure of a subject with a thermal stimulus while the subject is in a first activity state and reversing the reversible conduction block in the peripheral neural structure of the subject to permit conduction in the peripheral neural structure when the subject is in a second activity state (step 204).

The method of modulating neural activity as shown generally in FIG. 4 includes producing a reversible conduction block in a peripheral neural structure of a subject, which may be, for example, a peripheral nerve, a spinal root, an autonomic ganglion, or a nerve plexus. A peripheral nerve may be a sensory and/or motor nerve, an autonomic nerve (including sympathetic and/or parasympathetic nerve, or a mixture of sensory, motor, sensory-motor, and/or autonomic nerve fibers). Examples of specific nerves that may be subject to reversible conduction block include the radial nerve, median nerve, ulnar nerve, femoral nerve, obturator nerve, sciatic nerve, popliteal nerve, tibial nerve, peroneal nerve, and vagus nerve. The geniculate ganglion is an example of a specific ganglion that may blocked reversibly.

In the practice of the method outlined in FIG. 4, the first activity state and the second activity state may be defined in several different ways, depending upon the intended application of the method. In some cases, as discussed previously, the first and second activity states may represent first and second overall activity states of the subject, and in other cases, the use of a body portion innervated by the peripheral neural structure may be of interest, and the first and second activity states may represent first and second states of use of the innervated body portion.

FIG. 5 illustrates a sensed activity, represented by trace 250; activity state as determined from sensed activity, represented by trace 252; and several examples of blocking stimulus application patterns, which may be applied responsive to the sensed activity, represented by traces 254, 256 and 258. Time is indicated on the x-axis. Methods for delivering blocking stimuli responsive to and/or relative to sensed activity is described in greater detail in commonly owned U.S. patent application Ser. No. 11/999,721, which, as noted elsewhere herein, is incorporated herein by reference in its entirety. Trace 250 is an illustration of a sensed activity of the type that might be detected from a subject over a period of time. Trace 250 does not represent any specific type of signal (it could be, for example, a physiological signal such as a heart rate or respiration rate, or a physical signal such as motion detection or pressure signal). In this example, the activity in the subject is classified into one of two possible activity states, a first activity state and a second activity state, and it is assumed that higher values of the signal indicate that the subject is more active and lower values of the signal indicate that the subject is less active. By setting an appropriate threshold value, as indicated at 260, it may be possible to distinguish between the first activity state (during which the value of trace 250 is above the threshold value 260 and the second activity state (during which the value of trace 250 is below the threshold value 260). Trace 252 may be an overall activity state (which might be determined from heart rate, for example) or an activity or use state of a portion of the body of the subject (which might be determined from activity of a particular muscle, for example).

Examples of several representative patterns for application of blocking stimuli are also illustrated in FIG. 5. Trace 254 depicts a blocking stimulus pattern that corresponds directly to the activity state, with blocking stimulus applied (“on”) while the subject is in the first activity state and the blocking stimulus removed (“off”) while the subject is in the second activity state. The blocking stimulus pattern represented by trace 254 includes multiple blocking periods 270, 272, 274 and 276, during which a blocking stimulus sufficient to produce a reversible conduction block of at least a portion of the peripheral neural structure of the subject is applied, separated by release periods 280, 282 and 284, during which the blocking stimulus is reversed. Blocking periods 270, 272, 274 and 276 coincide with a first activity state in the subject and release periods 280, 282 and 284 coincide at least in part with a second activity state in the subject.

Trace 256 depicts a blocking stimulus pattern in which a blocking stimulus is applied at the onset of the first activity state and removed after a time t_(a) after the onset of the first activity state. Trace 258 depicts a blocking stimulus pattern in which a blocking stimulus is applied at a time t_(b) after the onset of the first activity state and removed at a time t_(c) after was applied. In this example, the period during which the blocking stimulus is applied or “on” may extend into the second activity state in the subject. Trace 252 indicates the activity state of the subject as thus determined.

A thermal stimulus may include a time-varying thermal stimulus, or a spatially-varying thermal stimulus. In some embodiments, the thermal stimulus may vary both spatially and temporally.

In some applications, the steps of producing a reversible conduction block in a peripheral neural structure of a subject while the subject is in a first activity state and reversing the reversible conduction block in the peripheral neural structure of the subject to permit conduction in the peripheral neural structure when the subject is in a second activity state may occur over a period of time sufficient to produce a modulation of an immune response in a region innervated by the peripheral neural structure.

In some applications, the steps of producing a reversible conduction block in a peripheral neural structure of a subject while the subject is in a first activity state and reversing the reversible conduction block in the peripheral neural structure of the subject to permit conduction in the peripheral neural structure when the subject is in a second activity state occur over a period of time sufficient to produce a modulation of an inflammatory response in a region innervated by the peripheral neural structure.

A blocking stimulus may be delivered intermittently responsive to activity state (for example according to a pattern as depicted in FIG. 5) until a desired modulation of an immune or inflammatory response is obtained. Modulation of an inflammatory or immune response may be produced using a method or system as described herein, and may involve the provision of total or partial blocking stimulus to a sensory nerve innervating a limb, join, or digit, to produce an effect e.g. as described in Kane et al., “Protective effect of sensory denervation in inflammatory arthritis (evidence of regulatory neuroimmune pathways in the arthritic joint),” Annals of Rheumatic Disease 2005; 64:325-327. doi: 10.1136/ard.2004.022277, or as described in Razavi et al., “TRPV1+ sensory neurons control β cell stress and islet inflammation in autoimmune diabetes,” (showing elimination of activity from sensory neurons innervating the pancreas may prevent development of diabetes); Cell; Dec. 15, 2006; pp. 1123-1135; Vol. 127, each of which is incorporated herein by reference in its entirety.

The amount of time needed to produce modulation of an immune response or inflammatory response may be determined prior to use of the method, based on experimental or clinical data, or the method may be carried out until an appropriate modulation of immune or inflammatory response is obtained as determined by measurement of indicators of immune or inflammatory response, as known to those of skill in the art. For example, inflammation may be indicated by one or more of swelling, color, temperature, or pain or tenderness, and these parameters may be determined qualitatively or quantitatively, as described in U.S. Pat. No. 7,226,426, which is incorporated herein by reference in its entirety. Inflammation may also be indicated by the presence of T-lymphocytes or macrophages, which may be detected immunohistochemically, for example as described in Rooney, T.; Bresnihan, B.; Andersson, U.; Gogarty, M.; Kraan, M.; Schumacker, H. R.; Ulfgren, A.-K.; Veale, D. J.; Youssef, P. P.; and Tak, P. P; “Microscopic measurement of inflammation in synovial tissue: inter-observer agreement for manual quantitative, semiquantitative and computerized digital image analysis”; Annals of Rheumatic Disease; 2007; Vol. 66, pp. 1656-1660; doi:10.1136/ard.2006.0611430; by eosinophils, cytokines, chemokines, and/or leukotrienes, as described in Howarth, P. H.; Persson, C. G. A.; Meltzer, E. O.; Jacobson, M. R.; Durhan, S. R.; and Silkoff, P. E.; “Objective monitoring of nasal airway inflammation in rhinitis”; J. Allergy Clin. Immunol.; 2005; Vol. 115; pp. S414-S441; and by other biomarkers, such as certain 14-3-3 proteins, as described in Kilani, R. T.; Maksymowych, W. P.; Aitken, A.; Boire, G.; St. Pierre, Y.; Li, Y.; and Ghahary, A.; “Detection of high levels of 2 specific isoforms of 14-3-3 proteins in synovial fluid from patients with join inflammation”; J. Rheumatology; 2007; Vol. 34, No. 8; pp. 1650-1657; each of which is incorporated herein by reference in its entirety. Inflammation may also be indicated by products of tissue degradation, and/or immune response may be indicated by one or more of antibodies, immune cells, or chemical markers of immune response or inflammation, as described in Poole, A. R.; “Immunochemical markers of joint inflammation, skeletal damage and repair: where are we now?”; Annals of Rheumatic Disease; 1994; Vol. 53; pp. 3-5; doi:10.1136/ard.53.1.3, which is incorporated herein by reference in its entirety.

The amount of time needed to produce modulation of an immune response or inflammatory response will depend upon a number of factors, including parameters of the blocking stimulus, the peripheral neural structure in which conduction block is produced, and the nature of the immune or inflammatory response of concern and the level of modulation that is to be produced.

FIG. 6 illustrates variants of the method shown generally in FIG. 4. The method of FIG. 6 includes the steps of producing a reversible conduction block in a peripheral neural structure of a subject with a thermal stimulus while the subject is in a first activity state (step 310), reversing the reversible conduction block in the peripheral neural structure of the subject to permit conduction in the peripheral neural structure when the subject is in a second activity state (step 312), receiving an input indicative of an activity state of the subject, wherein the input is indicative of at least one of a first activity state and a second activity state of the subject (314) and repeating the steps of producing a reversible conduction block in a peripheral neural structure of a subject with a thermal stimulus while the subject is in a first activity state and reversing the reversible conduction block in the peripheral neural structure of the subject to permit conduction in the peripheral neural structure when the subject is in a second activity state (step 316). In some embodiments, the method may include receiving an input representing physiological activity of the subject (as indicated at 318), which may include, for example, receiving an input representing the heart rate (as indicated at 320), respiration of the subject (as indicated at 322), brain activity (as indicated at 324), peripheral neural (as indicated at 326), muscle activity (as indicated at 328), or body temperature of the subject (as indicated at 330). Methods and devices for sensing these and other physiological signals or parameters are well known to those of skill in the art.

A physiological sensor as used in the method of FIG. 6 may be configured to generate a signal indicative of activity of the heart of the subject, activity of brain of the subject, activity of a peripheral neural system of the subject, activity of a muscle of the subject, respiration of the subject, body temperature of the subject, or other physiological signals that may be indicative of an activity state of all or a portion of the body of the subject. The detection of these and other physiological signals is known to those of skill in the art. Examples of some possible physiological signals that may indicate activity of all or a portion of a body of a subject include electroencephalographic signals (EEG), electromyographic signals (EMG), electrocardiographic signals (ECG), heart rate, blood pressure, blood oxygenation, respiration rate, respiratory volume, or body temperature. Receiving an input indicative of an activity state of the subject may include receiving an input representing a rest or waking state of the subject; for example, rest or waking state of a subject may be determined based on physiological parameters (EEG, heart rate, respiration rate, etc.). Specific activity states such as sleep may be indicated by particular chemical indicators, e.g. concentration of melatonin in body fluid or other measures (see, for example, U.S. Patent Publication 2005/0215947, which is incorporated herein by reference in its entirety).

In other embodiments, receiving an input indicative of an activity state of the subject may include receiving an input representative of physical activity of the subject (as indicated at 332 in FIG. 6). The method may include receiving an input representative of motion of the subject (as indicated at 334), receiving an input representative of the body position or posture of the subject (as indicated at 336), receiving an input from a pressure sensor (as indicated at 338), receiving an input from a force sensor (as indicated at 340), receiving an input from an accelerometer (as indicated at 342), receiving an input from a gyro (as indicated at 344), receiving an input from a switch (as indicated at 346), such as, for example a mercury switch, or receiving an input from a piezoelectric device (as indicated at 348). Other activity sensing devices, as known to those of skill in the art, may be used as well. In FIG. 6 and in other figures herein, boxes surrounded by dashed lines represent alternative or optional steps or system components.

A rest or waking state may be determined based on physical activity. For example, resting state may be associated with a lying down posture and/or low level of motion or activity, while a waking or active state may be associated with an upright posture and/or a higher level of activity. A physical activity sensor may be configured to generate a signal indicative of motion or acceleration of the at least a portion of the body of the subject innervated by the peripheral neural structure. In some embodiments, the physical activity sensor may be configured to generate a signal indicative of a body position or posture of the subject. Physical activity sensors may sense various aspects of posture or movement (amplitude, frequency, direction, etc.) and may include various types of sensors, singly or in combination. For example, see U.S. Pat. No. 5,031,618, which is incorporated herein by reference in its entirety.

Examples of physiological and physical sensors are provided in The Biomedical Engineering Handbook, Second Edition, Volume I, J. D. Bronzino, Ed., Copyright 2000, CRC Press LLC, section V, pp. V-1-51-9, which is incorporated herein by reference.

FIG. 7 illustrates further variants of the method shown generally in FIG. 4. The method of FIG. 7 includes the steps of producing a reversible conduction block in a peripheral neural structure of a subject with a thermal stimulus while the subject is in a first activity state (step 400), reversing the reversible conduction block in the peripheral neural structure of the subject to permit conduction in the peripheral neural structure when the subject is in a second activity state (step 402), receiving an input indicative of an activity state of the subject, wherein the input is indicative of at least one of a first activity state and a second activity state of the subject (404) and repeating the steps of producing a reversible conduction block in a peripheral neural structure of a subject with a thermal stimulus while the subject is in a first activity state and reversing the reversible conduction block in the peripheral neural structure of the subject to permit conduction in the peripheral neural structure when the subject is in a second activity state (step 406). The method further includes receiving an input indicative of a user instruction (as indicated at 408).

Receiving an input indicative of a user instruction may include receiving a signal from a user input device (as indicated at 410), which may include, for example, receiving a signal from a voice or sound activated input (as indicated at 412), a switch or knob (as indicated at 414), a keyboard (as indicated at 416), a mouse (as indicated at 418), a touch screen (as indicated at 420), or any sort of input device allowing a user to enter an instruction or select an option from a list of possible options, as known to those of skill in the art. User instructions may also be received from user-controlled intermediate device; e.g., a user instruction may be transmitted from a remote controller, a cell phone or remote computer operated by the user. The user may be a medical care provider, for example. Instructions may be transmitted electronically, electromagnetically, optically, acoustically, mechanically, or by other methods known to those of skill in the art, via one or more device or transmission media.

Receiving an input indicative of a user instruction may include receiving an input indicative of an instruction to modify a definition of a first activity state or receiving an input indicative of an instruction to modify a definition of a second activity state. For example, the definition of a first or second activity state may include a threshold level, e.g. as depicted in FIG. 5, at reference number 260.

As depicted in FIG. 7, receiving an input indicative of an activity state of the subject may in some embodiments include receiving an input indicative of a user instruction as an alternative to sensing a parameter indicative of the activity state of the subject (e.g., a physical or physiological activity). In other embodiments (not depicted), receiving an input indicative of a user instruction may be performed in addition to sensing a parameter indicative of the activity state of the subject. For example, a user input may be used to override delivery of blocking stimuli determined from a sensed parameter, or to modify a pattern of delivery of blocking stimuli.

A method as shown generally in FIGS. 4, 6 and 7 may include producing a reversible conduction block in a peripheral neural structure of a subject with a blocking stimulus source positioned in proximity to the body of the subject. In some embodiments, a blocking stimulus source worn on the body of the subject. For example, the blocking stimulus source may be located in or on a wrap adapted to be positioned around at least a portion of the body of the subject, in or on a bracelet, anklet, or cuff configured to be worn on a limb of the subject, or in or on a collar or necklace configured to be worn on a neck of the subject.

FIG. 8 depicts an embodiment of a neural modulation system 450 that includes a signal input structure 452 configured to receive a signal 454 indicative of an activity state of at least a portion 456 (in this case, the forearm) of a body of a subject 458 innervated by a peripheral neural structure 460, a signal processing portion 462 configured to distinguish a first activity state of the at least a portion 456 of the body of the subject 458 innervated by the peripheral neural structure 460 from a second activity state of the at least a portion 456 of the body of the subject 458 innervated by the peripheral neural structure 460 from the signal 454 received at the signal input structure 452 and generate a blocking stimulus control signal 464 for driving production of a thermal blocking stimulus configured to reversibly block conduction in the peripheral neural structure 460 of the subject during at least a portion of the first activity state, and a blocking stimulus source 466 configured to be worn on the body of the subject 458 and to produce a thermal blocking stimulus responsive to the blocking stimulus control signal 464. Signal 454 may be produced by sensor 468 in response to activity of portion 456 of body of subject 458. Sensor 468 may be, for example, an electrode for sensing electromyographic (EMG) activity reflective of muscle activity.

The blocking stimulus source may be located in or on a wrap adapted to be positioned around at least a portion of the body of the subject, in or on a bracelet, anklet, or cuff configured to be worn on a limb of the subject or collar or necklace configured to be worn on a neck of the subject. In some embodiments, the signal processing portion may also be configured to be worn on the body of the subject. The signal processing portion may be packaged with the blocking stimulus source in a package configured to be worn on the body of the subject, e.g. as shown in FIG. 8. In other embodiments, the signal processing portion may be configured to be located at a location remote from the body of the subject. FIG. 8 illustrates an embodiment of a system in which a blocking stimulus source 466 is located in an arm band (or bracelet/cuff) 470 configured to be worn on a forearm 456 of a subject. Blocking stimulus source 466 includes a Peltier device configured so that the cool side is adjacent the skin of forearm 456.

In this and other embodiments in which the blocking stimulus source is worn on the body of the subject or otherwise positioned in proximity to the body of the subject, the blocking stimulus source (e.g. blocking stimulus source 160 in FIG. 3 or 460 in FIG. 8) may include a cooling device placed on the skin of a subject over a neural structure for blocking conduction in the neural structure. Cooling devices may include Peltier or thermoelectric coolers, e.g. as described in U.S. Pat. Nos. 5,830,208; 6,248,126; and 7,244,253; evaporative or heat transfer elements or devices, e.g. as described in U.S. Pat. Nos. 5,057,104; 6,364,899; and 7,204,832; or devices including combinations of heat transfer elements or mechanisms, e.g., a combinations of a thermoelectric device and fluid heat transfer mechanism, as described in U.S. Pat. No. 6,746,747. Each of the preceding references is incorporated herein by reference in its entirety. In other embodiments, cooling may be produced by an endothermic reaction (such as the mixing of ammonium nitrate and water) initiated, for example, by opening of a valve or actuation of a container. Cooling may also be provided by a pre-cooled thermal mass (e.g., a metal block, a fluid or a gel). Other cooling devices and mechanisms, as known to those of skill in the relevant arts, may also be used. Blocking may be produced with a cooling thermal stimulus applied for the duration of the blocking period, or with a pulsatile heating stimulus applied at a high frequency to produce blocking of neural structures. A high frequency pulsatile heating stimulus may be applied in combination with cooling applied substantially continuously throughout the blocking period, so that the pulsatile heating stimulus produces transient increases in temperature that may lead to conduction block while the cooling prevents overheating of tissue to a degree that would result in tissue damage.

High frequency electrical stimulation is known to produce reversible nerve conduction block, with larger diameter fibers having lower blocking thresholds, e.g. as described in the following references, each of which is incorporated herein by reference in its entirety: V. Krauthamer & T. Crosheck, Med. Biol. Eng. Comput., “Effects of high-rate electrical stimulation upon firing in modeled and real neurons,” 2002, 40, 360-366; K. L Kilgore & N. Bhadra, “Nerve conduction block utilising high-frequency alternating current,” Med. Biol. Eng. Comput., 2004, 42, 394-406; C. Tai, W. C. de Groat, and J. R. Roppolo “Simulation analysis of conduction block in unmyelinated axons induced by high-frequency biphasic electrical currents,” IEEE Trans. Biomed. Engr., vol. 52, No. 7, July 2005, pp. 1323-1332; X. Zhang, J. R. Roppolo, W. C. de Groat, and C. Tai, “Simulation analysis of conduction block in myelinated axons induced by high-frequency biphasic rectangular pulses,” IEEE Trans. Biomed. Engr., Vol. 53, No. 7, July 2006, pp. 1433-1436; and X. Zhang, J. R. Roppolo, W. C. de Groat, and C. Tai, “Mechanism of nerve conduction block induced by high-frequency biphasic electrical currents,” IEEE Trans. Biomed. Engr., Vol. 53, No. 12, December 2006, pp. 2445-2454.

High frequency stimulation may include high frequency thermal stimulation, rather than electrical stimulation. A high frequency pulsatile heating stimulus may be any type of stimulus that produces stimulation through a thermal mechanism. For example, it is thought that the underlying mechanism for optical stimulation of nerve is a thermal mechanism (e.g., heating), as described in Wells et al.; “Pulsed laser versus electrical energy for peripheral nerve stimulation”; Journal of Neuroscience Methods; 2007; Vol. 163; pp. 326-337; and Wells et al.; “Biophysical mechanisms of transient optical stimulation of peripheral nerve; Biophysical Journal; October 2007; pp. 2567-2580; Volume 93, both of which are incorporated herein by reference in their entirety. As noted above, in order to avoid tissue damage from excessive heating produced by high frequency pulsatile heating stimuli, cooling may be applied substantially continuously throughout the blocking period to provide an ambient baseline temperature upon which transient heating pulses may be superimposed. See also J. Wells, C. Kao, E. D. Jansen, P. Konrad, A. Mahadevan-Jansen, “Application of infrared light for in vivo neural stimulation,” J. Biomedical Optics 10(6) 064003 (November/December 2005), which is also incorporated herein by reference.

Optical sources suitable for neural stimulation include, for example, a Holmium:YAG laser (wavelength 2.12 μm), a laser diode (wavelength 1.8-2.2 μm), an LED (e.g., at wavelength 880 nm, 940 nm, or 1.87 μm), a diode-pumped solid-state laser (wavelength 2.2 μm), or a Free Electron Laser (FEL. Optical neural stimulation methods and devices are described, for example, in U.S. Pat. No. 6,921,413 and U.S. Published Patent Applications 20080077198, 20050216072, and 20060282134, each of which is incorporated herein by reference in its entirety.

Ultrasonic stimuli may also produce thermal stimulation and blocking, e.g., as described in C. Z. Hong, “Reversible nerve conduction block in patients with polyneuropathy after ultrasound thermotherapy at therapeutic dosage,” Arch. Phys. Med. Rehabil. February 1991; 72(2):132-137; S. J. Norton, “Can ultrasound be used to stimulate nerve tissue?” BioMedical Engineering OnLine 2003, 2:6; and P.-H. Tsui, S.-H. Wang and C. C. Huang, “In vitro effects of ultrasound with different energies on the conduction properties of neural tissue,” Ultrasonics 43 (2005) 560-565. used excised bullfrog sciatic nerve; each of which is incorporated herein by reference in its entirety.

As used herein with reference to thermal stimuli, “high frequency stimulation” refers to a stimulus delivered at a frequency that is high enough to produce blockage of conduction in a nerve fiber. The stimulus frequency at which conduction may be blocked may depend on the diameter of the fiber or fibers to be blocked, the stimulus configuration (e.g. stimulus pulse waveform, duration, and spatial distribution); ambient baseline temperature, etc., and may be determined by one of skill in the art. For example, the materials incorporated herein by reference provide guidance with regard to selection of stimulation frequency and other parameters. Without limitation, frequencies sufficient to produce a conduction block may include frequencies from about 90 Hz to about 100 Hz, from about 100 Hz to about 500 Hz, from about 500 Hz to about 1 kHz, from about 1 kHz to about 2 kHz, from about 3 kHz to about 5 kHz, or from about 2 kHz to about 20 kHz. High frequency conduction stimulation may produce a reversible conduction block, or, if the stimulation frequency is high enough to cause excessive heating of tissue, high frequency stimulation may produce an irreversible conduction block. Optical stimulation may be delivered with an implantable nerve cuff containing light emitters, e.g. of the type described in U.S. Published Patent Application 20060155348, which is incorporated herein by reference in its entirety. Other methods/mechanisms may be used for generating heating thermal stimuli, including but not limited to exothermic reaction devices.

FIG. 9 illustrates a number of blocking stimulus patterns. In some embodiments, a blocking stimulus sufficient to produce a reversible conduction block of at least a portion of a peripheral neural structure of a subject may be applied substantially continuously during the blocking period. Trace 500 represents the activity state of a subject as a function of time, as indicated on axis 562. Trace 510 depicts an example of a blocking stimulus that is applied substantially continuously during each blocking period, with the blocking periods corresponding to occurrences of a first activity state, as indicated in trace 500. Such an application pattern may be appropriate for application of a stimulus that produces blocking by hyperpolarization of axonal membranes.

In other embodiments, a blocking stimulus sufficient to produce a reversible conduction block of at least a portion of a peripheral neural structure of a subject may be applied intermittently during the blocking period. For example, a blocking stimulus sufficient to produce a reversible conduction block of at least a portion of a peripheral neural structure of a subject may be applied intermittently at a fixed repetition rate during the blocking period. A high frequency stimulus as described elsewhere herein is an example of a blocking stimulus that is applied intermittently. Traces 520 and 530 in FIG. 9 are two examples of blocking stimuli applied intermittently during the blocking period. Blocking stimuli may include different combinations of pulse duration, pulse amplitude, pulse frequency, duty cycle, etc. In trace 530, pulse amplitude varies over time during the blocking period. In trace 540 pulse duration and interval vary over time during the blocking period. In some embodiments, the blocking stimulus may be applied according to a programmed pattern during at least a portion of the blocking period. The programmed pattern may specify a blocking stimulus amplitude that varies over time during the blocking period, as depicted in trace 550. In addition, a programmed pattern may specify application of blocking stimulus pulses intermittently during the blocking period in which the amplitude of the stimulus pulses varies over time during the blocking period, as illustrated in trace 530, or in which one or both of the duration of the stimulus pulses or interval between the stimulus pulses varies over time during the blocking period, as illustrated in trace 540.

Various configurations of stimulus may be used; while for simplicity rectangular pulses have been depicted in most of the figures, the pulse may ramp up gradually when it is applied, and/or may decay gradually when removed, as depicted in Trace 560 of FIG. 9, or may have various other waveforms, as illustrated in trace 550.

A reversible conduction block may be produced utilizing various types of thermal blocking stimuli. For example, producing a reversible conduction block may include applying a thermal stimulus to at least a portion of the peripheral neural structure. The thermal stimulus may include a static cooling, pulsed cooling or a high-frequency pulsed thermal stimulus, which may be applied in combination with static cooling. In some embodiments, producing a reversible conduction block may include applying a pulsed thermal blocking stimulus to at least a portion of the peripheral neural structure. In still other embodiments, producing a reversible conduction block may include applying an oscillating thermal stimulus, or other cyclical, periodic, or time-varying thermal stimulus to at least a portion of the peripheral neural structure.

Methods as described herein may include storing or saving information regarding device operation on the device, or transmitting such information to a remote location for storage or evaluation. Information may include, but is not limited to including device settings, parameters and other information relating to production of blocking and reversing stimuli, and sensed activity level or activity state of a subject, regarding producing a reversible conduction block.

In some embodiments, methods as described herein may include producing a reversible conduction block in a peripheral neural structure of a subject with a blocking stimulus source configured to be positioned beneath at least a portion of the body of the subject. For example, in various embodiments, the blocking stimulus source may be located in or on a chair, bed, pad, cushion, or any other structure on which at least a portion of the body of the subject may rest. If only a portion of the subject's body is to be subjected to the blocking stimulus, a structure having a size and structure suited to the portion of the body may be used. For example, if the body portion is the lower leg, the blocking stimulus source may be included in a footstool, for example. If the body portion is the arm, the blocking stimulus source may be included in a table top, arm rest, or sling. If the blocking stimulus source is included in a pad or cushion of an appropriate size, the pad or cushion may be placed on any surface (a chair, stool, table top, the subject's lap, a bed, the ground, etc.) and the body portion may then be positioned above the pad or cushion.

FIG. 10 depicts an embodiment of a neural modulation system 600 in which a blocking stimulus source 602 is located in chair 604 on which the subject 606 may be seated. In the embodiment of FIG. 10, neural modulation system 600 includes a signal input structure 608 configured to receive a signal 610 indicative of an activity state of at least a portion 612 of a body of a subject 606 innervated by a peripheral neural structure 614, a signal processing portion 616 configured to distinguish a first activity state of the at least a portion 612 of the body of the subject 606 innervated by the peripheral neural structure 614 from a second activity state of the at least a portion 612 of the body of the subject 606 innervated by the peripheral neural structure 614 from the signal 610 received at the signal input structure 608 and generate a blocking stimulus control signal 618 for driving production of a thermal blocking stimulus 620 configured to reversibly block conduction in the peripheral neural structure 614 of the subject during at least a portion of the first activity state, and blocking stimulus source 602 configured to be positioned beneath at least a portion 612 of the body of the subject 606 and to produce a thermal blocking stimulus 620 responsive to the blocking stimulus control signal 618. Blocking stimulus source 602 may be configured to be located in or on a chair 604, as depicted in FIG. 10. Blocking stimulus source 602 may be a fluid heat transfer device including fluid channel 624 carrying a coolant fluid, and fluid cooler/pump 626. Fluid cooler/pump 626 cools the coolant fluid and causes it to circulate through fluid channel 624, which is arranged so that it lies beneath portion 612 (i.e., the upper leg) of the body of subject 606. The coolant fluid thus absorbs heat from the upper leg to produce cooling thereof. Signal 610, which is indicative of an activity state of a least portion 612 of the body of the subject 606, may be produced by a sensor 622, which in the present example is a pressure that is activated when subject 606 sits in chair 604. In the present example, it is presumed that portion 612 (the limb of the subject) is substantially immobile and inactive when subject 606 is sitting.

FIG. 11A depicts an embodiment of a system in which a blocking stimulus source is located in a bed 650 upon which the subject 652 lies. FIG. 11B shows a portion of the system of FIG. 11A in greater detail. In the embodiment of FIGS. 11A and 11B, a subject 652 rests on a bed 650. Blocking stimulus source 654 is positioned below a portion 656 of the body of subject 652. In the present example, blocking stimulus source 654 includes static cooling source 668 and multiple acoustic sources 670, which function as heating stimulus sources capable of producing pulsed transient heating stimuli. Static cooling source 668 may be any cooling source capable of producing substantially constant cooling during the blocking period. As used herein, the term “static cooling” refers to cooling that is applied substantially continuously or steadily for a period of time, typically substantially coincident with the blocking period. Static cooling source 668 may include a Peltier cooler, a fluid heat-transfer mechanism (including a circulating coolant fluid), or other cooling sources or mechanisms as are known to those of skill in the art. Acoustic sources 670 may be, for example, ultrasound sources, that are aimed and focused so that acoustic pulses produce constructive interference to maximize acoustic energy at the areas of overlap. Static cooling source 668 is a primary blocking stimulus source and acoustic sources 670 together form a secondary blocking stimulus source. The acoustic energy may be provided at a level sufficient to produce heating at the areas of overlap, which may be selected to coincide with peripheral neural structures to be blocked (e.g., nerves 672 and 674 as depicted in FIGS. 11A and 11B.) As described elsewhere herein, the transient heating pulses produced by the overlapping acoustic pulses may be sufficient to block conduction in the peripheral neural structures, while the cooling from static cooling source 668 prevents overheating of tissue.

User input device 658 (in this example, a switch device including a push-button 660 that may be depressed by subject 652 to indicate the beginning and end of a rest period) provides a signal 662 to signal processing portion 664 on cable 666, representing the activity state of the subject. As described in connection with other embodiments, signal processing portion 664 controls production of a blocking stimulus by blocking stimulus source 654.

FIG. 11A and 11B depict an example of a neural modulation system in which the blocking stimulus source includes a primary blocking stimulus source configured to produce a primary thermal blocking stimulus component and a secondary blocking stimulus source configured to produce a secondary thermal blocking stimulus component. The primary thermal blocking stimulus component and the secondary thermal blocking stimulus component act together to reversibly block conduction in the peripheral neural structure. The signal processing portion 664 is configured to generate a blocking stimulus control signal including a primary blocking stimulus control signal 676 for driving production of the primary thermal blocking stimulus component and a secondary blocking stimulus control signal 678 for driving production of the secondary thermal blocking stimulus component. In the example of FIGS. 11A and 11B, the primary blocking stimulus source includes a static cooling stimulus source and the secondary blocking stimulus source includes a pulsed transient heating stimulus source.

In the use of a system as illustrated in FIGS. 11A and 11B, producing a reversible conduction block in a peripheral neural structure of a subject with a thermal stimulus includes producing a primary thermal blocking stimulus component and producing a secondary thermal blocking stimulus component, wherein the primary thermal blocking stimulus component and the secondary thermal blocking stimulus component act together to reversibly block conduction in the peripheral neural structure. In the specific example depicted in FIGS. 11A and 11B, the primary thermal stimulus component includes static cooling stimulus and the secondary thermal stimulus component includes a pulsed transient heating stimulus.

A method as illustrated generally in, e.g. FIG. 4, may in some embodiments include producing a reversible conduction block in a peripheral neural structure of a subject with a blocking stimulus source implanted within the body of the subject.

FIG. 12 depicts an embodiment of a system in which a blocking stimulus source is implanted within the body of the subject. Neural modulation system 700 as depicted in FIG. 12 includes signal input structure 702 configured to receive a signal 704 indicative of an activity state of at least a portion 706 of a body of a subject 708 innervated by a peripheral neural structure 710, a signal processing portion 712 configured to distinguish a first activity state of the at least a portion 706 of the body of the subject 708 innervated by the peripheral neural structure 710 from a second activity state of the at least a portion 706 of the body of the subject 708 innervated by the peripheral neural structure 710 from signal 704 received at the signal input structure 702 and generate a blocking stimulus control signal 714 for driving production of a thermal blocking stimulus 716 configured to reversibly block conduction in the peripheral neural structure 710 of subject 708 during at least a portion of the first activity state, and a blocking stimulus source 718 configured to be implanted within the body of the subject 708 and to produce a thermal blocking stimulus 716 responsive to the blocking stimulus control signal 714. As can be seen in greater detail in the inset, in this example, blocking stimulus source 718 includes Peltier devices 720 and 722 in thermally insulating cuff 726. Peltier devices 720 and 722 are configured to produce cooling of peripheral neural structure 710 sufficient to block conduction, and may be driven by a power source within or external to the body of the subject, via a wired or wireless connection (see, e.g. US 2006/0190053, which is incorporated herein by reference in its entirety.) In the example of FIG. 12, blocking stimulus source 716 is implanted, but the neural modulation system 700 includes an external portion 726, which may be worn on the wrist in a manner similar to a wristwatch. In the embodiment of FIG. 12, external portion 726 includes signal processing portion 712 and sensor 728, a motion sensor which detects movement of portion 706 of the body of subject 708, and generates signal 704, which is provided to signal input structure 702, as discussed above. Heat from Peltier devices 720 and 722 may be dissipated into tissue surrounding thermally insulating cuff 726, or may be conducted to a more distant location, within or at the surface of the body, by a metallic or fluid conductor, to prevent thermal damage to surrounding tissue.

FIG. 13 depicts a related method, which includes the steps of producing a reversible conduction block in a peripheral neural structure of a subject with a thermal stimulus while the subject is in a first activity state at 750; reversing the reversible conduction block in the peripheral neural structure of the subject to permit conduction in the peripheral neural structure when the subject is in a second activity state at 752; wherein the method further includes reversing the reversible conduction block in the peripheral neural structure of the subject to permit conduction in the peripheral neural structure when the subject is in a second activity state by removing a blocking stimulus used to produce the reversible conduction block in the peripheral neural structure of the subject, as indicated at 754; and repeating the steps of producing a reversible conduction block in a peripheral neural structure of a subject with a thermal stimulus while the subject is in a first activity state and reversing the reversible conduction block in the peripheral neural structure of the subject to permit conduction in the peripheral neural structure when the subject is in a second activity state, as indicated at 756.

In some embodiments, a neural modulation system may include a signal input structure configured to receive a signal indicative of an activity state of at least a portion of a body of a subject innervated by a peripheral neural structure, a signal processing portion configured to distinguish a first activity state of the at least a portion of the body of the subject innervated by the peripheral neural structure from a second activity state of the at least a portion of the body of the subject innervated by the peripheral neural structure from the signal received at the signal input structure, generate a blocking stimulus control signal for driving production of a thermal blocking stimulus configured to reversibly block conduction in the peripheral neural structure of the subject during at least a portion of the first activity state and generate a release stimulus control signal for controlling discontinuation of production of the electrical field blocking stimulus when the subject is in the second activity state, a sensor operatively connected to the signal input structure and configured to generate the signal indicative of an activity state of at least a portion of a body of a subject innervated by a peripheral neural structure responsive to an activity of the at least a portion of the body of the subject, and a blocking stimulus source configured to produce a thermal blocking stimulus responsive to the blocking stimulus control signal. A release stimulus control signal may be delivered to the blocking stimulus source from the signal processing portion on the same line or channel as the blocking stimulus control signal, or it may be provided on a separate line or channel.

The signal processing portion may be configured to repetitively generate the blocking stimulus control signal for driving production of a thermal blocking stimulus configured to reversibly block conduction in the peripheral neural structure of the subject during at least a portion of the first activity state and the release stimulus control signal for controlling discontinuation of production of the blocking stimulus when the subject is in the second activity state.

In some embodiments, the signal processing portion may be configured to repetitively generate the blocking stimulus control signal for driving production of a thermal blocking stimulus configured to reversibly block conduction in the peripheral neural structure of the subject during at least a portion of the first activity state and the release stimulus control signal for controlling discontinuation of production of the electrical field blocking stimulus when the subject is in the second activity state over a period of time sufficient to produce modulation of an immune response in a region innervated by the peripheral neural structure. Modulation of immune response may be assessed according to methods as discussed elsewhere herein.

In some embodiments, the signal processing portion may be configured to generate the blocking stimulus control signal for driving production of a thermal blocking stimulus configured to reversibly block conduction in the peripheral neural structure of the subject during at least a portion of the first activity state and the release stimulus control signal for controlling discontinuation of production of the electrical field blocking stimulus when the subject is in the second activity state cyclically, wherein each cycle includes a blocking period during which a thermal blocking stimulus sufficient to produce reversible conduction block in a peripheral neural structure of a subject is produced while the subject is in a first activity state and a release period during which no electrical field blocking stimulus is delivered, e.g., as illustrated in FIG. 5.

The signal processing portion may be configured to generate the blocking stimulus control signal for driving production of a thermal blocking stimulus configured to reversibly block conduction in the peripheral neural structure of the subject during at least a portion of the first activity state and the release stimulus control signal for controlling discontinuation of production of the electrical field blocking stimulus when the subject is in the second activity state cyclically at a rate of one cycle per day.

The signal processing portion may be configured to generate the electrical field blocking stimulus control signal for driving production of a thermal blocking stimulus configured to reversibly block conduction in the peripheral neural structure of the subject during at least a portion of the first activity state and generate the release stimulus control signal for controlling discontinuation of production of the electrical field blocking stimulus when the subject is in the second activity state in alternation according to a pre-set schedule.

Repetitive or cyclical generation of blocking stimuli may be performed as described herein, under the control of software, hardware, or other electrical circuitry by methods known to those of skill in the art.

As shown in FIG. 14, a method of modulating neural activity may include producing a reversible conduction block in a peripheral neural structure of a subject with a thermal stimulus while the subject is in a first activity state (step 800), reversing the reversible conduction block in the peripheral neural structure of the subject to permit conduction in the peripheral neural structure when the subject is in a second activity state by applying a reversing stimulus configured to counter the blocking stimulus used to produce the reversible conduction block in the peripheral neural structure of the subject (step 802), and repeating the steps of producing a reversible conduction block in a peripheral neural structure of a subject while the subject is in a first activity state and reversing the reversible conduction block in the peripheral neural structure of the subject to permit conduction in the peripheral neural structure when the subject is in a second activity state (step 804).

A reversing stimulus may be any stimulus sufficient to counter the blocking stimulus and return the nerve to a normally conductive state. A reversing stimulus may be of the same type or modality as the blocking stimulus (e.g., if the blocking stimulus is a cooling thermal stimulus, the reversing stimulus may be a warming thermal stimulus) or a reversing stimulus may be of a different type or modality than the blocking stimulus (e.g., the blocking stimulus may be a high-frequency pulsed thermal stimulus, and the reversing stimulus may be an electrical stimulus, a magnetic stimulus, an electromagnetic stimulus, a chemical stimulus, or a static or steady state thermal stimulus). The reversing stimulus may cancel or oppose the effect of the blocking stimulus, and may be delivered with either the same stimulus source as the blocking stimulus, or another stimulus source.

FIG. 15 illustrates an embodiment of a neural modulation system 850 that includes separate blocking stimulus source and reversing stimulus source. Neural modulation system 850 includes a signal input structure 852 configured to receive a signal 854 indicative of an activity state of at least a portion 856 of a body of a subject innervated by a peripheral neural structure 860, and a signal processing portion 862 configured to distinguish a first activity state of the at least a portion 856 of the body of the subject innervated by the peripheral neural structure 860 from a second activity state of the at least a portion 856 of the body of the subject innervated by the peripheral neural structure 860 from signal 854 received at signal input structure 852, generate blocking stimulus control signal 864 for driving production of a thermal blocking stimulus 866 configured to reversibly block conduction in the peripheral neural structure 860 of the subject during at least a portion of the first activity state, and generate a reversing stimulus control signal 868 for driving production of a reversing stimulus 870 to counter electrical field blocking stimulus 866 used to produce the reversible conduction block in the peripheral neural structure 860 of the subject, a blocking stimulus source 872 configured to produce a thermal blocking stimulus 866 responsive to the blocking stimulus control signal 864, and a reversing stimulus source 874 configured to produce a reversing stimulus 870 responsive to the reversing stimulus control signal 868.

The reversing stimulus may be any type of stimulus that serves to reverse the effect of the blocking stimulus to bring the neural structure back to (or toward) its previous conductivity state. In some embodiments, the reversing stimulus source may be of the same type as the blocking stimulus source; when a cooling thermal blocking stimulus is used, for example, the reversing stimulus source may include a warming thermal reversing stimulus source. In some embodiments, the reversing stimulus source may include at least a portion of the blocking stimulus source, while in other embodiments, the reversing stimulus source may be a different or separate stimulus source of the same type as the blocking stimulus source. In some embodiments, the reversing stimulus source may include a different type of stimulus source than the blocking stimulus source. For example, in a neural modulation system that includes a cooling blocking stimulus source, the reversing stimulus source may include one or more of a magnetic field source, an electric field source, an electromagnetic transducer, an optical photon source, an acoustic energy source, or a chemical agent source.

Applying a reversing stimulus to counter the blocking stimulus used to produce the reversible conduction block in the peripheral neural structure of the subject may include applying an electric or magnetic field to at least a portion of the peripheral neural structure. The electric or magnetic field used as a reversing stimulus may be a pulsed electric or magnetic field applied to at least a portion of the peripheral neural structure, or it may be cyclical or time-varying electric or magnetic field.

In some embodiments, applying a reversing stimulus to counter the blocking stimulus used to produce the reversible conduction block in the peripheral neural structure of the subject may include applying electromagnetic energy to at least a portion of the peripheral neural structure. Applying a reversing stimulus to counter the blocking stimulus used to produce the reversible conduction blocking in the peripheral neural structure of the subject may include heating or cooling at least a portion of the peripheral neural structure.

FIG. 16 shows a further extension of the method of modulating neural activity outlined in FIG. 4. The method includes producing a reversible conduction block in a peripheral neural structure of a subject with a thermal stimulus while the subject is in a first activity state (step 900), reversing the reversible conduction block in the peripheral neural structure of the subject to permit conduction in the peripheral neural structure when the subject is in a second activity state (step 902), repeating the steps of producing a reversible conduction block in a peripheral neural structure of a subject with a thermal stimulus while the subject is in a first activity state and reversing the reversible conduction block in the peripheral neural structure of the subject to permit conduction in the peripheral neural structure when the subject is in a second activity state (step 904), determining that producing the reversible conduction block in the peripheral neural structure of the subject with a thermal stimulus while the subject is in a first activity state results in a desired effect in the subject (step 906), and producing a non-reversible conduction block in the peripheral neural structure of the subject (step 908). A desired effect may be, for example, reduction or elimination of pain, undesired sensations, inflammation, immunological or physiological problems caused or contributed to by peripheral neural activity in the blocked peripheral neural structure. Determination that a desired effect has been produced may be made through sensing of various physiological or physical parameters, or by qualitative or subjective reporting obtained from the subject.

A non-reversible conduction block may be produced in various ways. As shown in further detail in FIG. 17, a method including steps 900, 902, 904, 906 and 908 (as described in connection with FIG. 16) may include producing a non-reversible conduction block by applying heat to at least a portion of the peripheral neural structure of the subject (as indicated at 910), for example with a Peltier device. Various other techniques can be used to apply heat, without limitation, as are known to those of skill in the art. Some examples include: electrical current, optical photons, ultrasound, the use of a resistive heater, an exothermic reaction, etc. See, for example, U.S. Published Patent Application 2005/0288730, which is incorporated herein by reference. Heat may cause non-reversible conduction block by various mechanisms, e.g. thermal ablation of tissue or stimulation of apoptosis. See, for example, the method as disclosed in U.S. Pat. No. 6,405,732, which is incorporated herein by reference in its entirety. The present method is not limited to any particular mechanism of producing a non-reversible conduction block through application of heat. A non-reversible conduction block may be produced by cooling or removing heat from at least a portion of the peripheral neural structure of the subject (as indicated at 912), for example with a Peltier device or with a fluid heat transfer device, applying an electrical current to at least a portion of the peripheral neural structure of the subject (as indicated at 914), delivering acoustic energy to at least a portion of the peripheral neural structure of the subject (as indicated at 916), delivering photons to at least a portion of the peripheral neural structure of the subject (as indicated at 918), delivering a chemical agent (e.g. capsaicin) to least a portion of the peripheral neural structure of the subject (as indicated at 920), or by surgical transection of at least a portion of the peripheral neural structure of the subject (as indicated at 922).

Producing a reversible conduction block may include producing substantially complete blockage of conduction in the peripheral neural structure of the subject. Alternatively, in some cases only partial blockage of conduction may be obtained, e.g. as depicted in FIGS. 2E and 2F. Completeness of blockage may be assessed by measuring neural activity by known methods by delivering a well-defined stimulus on one side of the blocked region and measuring the evoked neural activity on the other side of the blocked region and, optionally, comparing the evoked activity to activity measured at the same site prior to blocking of conduction or at an location upstream of the block, either before or after blocking.

FIG. 18 depicts a further embodiment of a neural modulation system that is similar to previously described systems, but in addition includes a non-reversible blocking source. Neural modulation system 925 may include signal input structure 927 configured to receive signal 929 indicative of an activity state of at least a portion 931 of a body of a subject innervated by a peripheral neural structure 935, and a signal processing portion 937 configured to distinguish a first activity state of the at least a portion 931 of the body of the subject innervated by the peripheral neural structure 935 from a second activity state of the at least a portion 931 of the body of the subject innervated by the peripheral neural structure 935 from signal 929 received at signal input structure 927 and generate a blocking stimulus control signal 939 for driving production of a thermal blocking stimulus configured to reversibly block conduction in the peripheral neural structure 935 of the subject during at least a portion of the first activity state, determine that producing the reversible conduction block in peripheral neural structure 935 of the subject while the subject is in a first activity state results in a desired effect in the subject, and generate a non-reversible blocking source control signal 941 for driving a non-reversible blocking source 943 to perform an action adapted for producing a non-reversible conduction block in peripheral neural structure 935 of the subject, a blocking stimulus source 947 configured to produce a thermal blocking stimulus responsive to the blocking stimulus control signal 939, and a non-reversible blocking source 943 configured to perform an action adapted for producing a non-reversible conduction block in the peripheral neural structure of the subject responsive to the non-reversible blocking source control signal.

FIG. 18 depicts a system 925 in which blocking stimulus source 947 is a thermally insulating cuff 951 including Peltier devices 953 (configured to cool peripheral neural structure 935), and non-reversible blocking source 943, which in this example is an electrode which can function as a heating element and which may also be used for sensing neural activity from peripheral neural structure 935. The sensed neural activity may be provided as signal 929 to signal input structure 927, to serve as a source of information regarding activity of the portion 931 of the body of the subject innervated by peripheral neural structure 935. In the example of FIG. 18, peripheral neural structure 935 innervates the region of joint 957. Non-reversible blocking source 943 may be configured to produce thermal ablation of at least a portion of the peripheral neural structure of the subject, or to stimulate apoptosis in the peripheral neural structure, for example, and the practice of the invention is not limited to any particular mechanism for producing non-reversible blocking. Alternatively, a heat source may include, but is not limited to, an appropriately configured Peltier device, a light source, a fluid heat-transfer device, or an acoustic element.

In some embodiments, the blocking stimulus source may be configured to produce a spatially varying thermal blocking stimulus. A spatially varying thermal blocking stimulus may be produced, for example, by a blocking stimulus source that includes a plurality of spatially distributed thermal stimulus sources, which may be distributed circumferentially around the nerve, as depicted in FIG. 18, or in other distributions, including but not limited to, a longitudinal distribution along the nerve or an array disposed over or around the nerve. A plurality of spatially distributed thermal stimulus sources may include a plurality of stimulus sources all of the same type, or may include different types of thermal stimulus sources, for example, at least one cooling stimulus source and at least one heating stimulus source. In some cases, a plurality of spatially distributed thermal stimulus sources may include at least one stimulus source that is configurable as either a heating stimulus source or a cooling stimulus source. For example, a Peltier device may be configured as either a heating stimulus source or a cooling stimulus source by reversing the current through the device.

In other embodiments, the non-reversible blocking source may include a cooling source, such as an appropriately configured Peltier device or a reservoir containing a chemical composition or mixture capable of undergoing a controllable endothermic reaction. In other embodiments, the non-reversible blocking source may include an electrical current source, and acoustic energy source, a photon source, or a chemical agent source. In general, a non-reversible blocking source may be any source of any type of energy, material, or action sufficient to damage or destroy the peripheral neural structure to produce permanent (or substantially permanent) blockage of nerve conduction. As a further example, in some embodiments, the non-reversible blocking source may include a surgical transection mechanism.

FIG. 19 illustrates a further variant of a method of modulating neural activity, which may include producing a reversible conduction block of a subset of nerve fibers in a peripheral neural structure of a subject with a thermal stimulus while the subject is in a first activity state (step 950), reversing the reversible conduction block of the subset of nerve fibers in the peripheral neural structure of the subject to permit conduction in the subset of nerve fibers in the peripheral neural structure when the subject is in a second activity state (step 952), and repeating the steps of producing a reversible conduction block in the subset of nerve fibers in a peripheral neural structure of a subject with a thermal stimulus while the subject is in a first activity state and reversing the reversible conduction block in the subset of nerve fibers in the peripheral neural structure of the subject to permit conduction in the subset of nerve fibers in the peripheral neural structure when the subject is in a second activity state (step 954). In different variations of the method (indicated with dashed boxes in FIG. 19) the subset of nerve fibers in the peripheral neural structure of the subject may include nerve fibers within a selected diameter range (as indicated at 956), within a selected spatial distribution within the peripheral neural structure (as indicated at 958), within selected fascicles and/or within the peripheral neural structure (as indicated at 960). Various methods of exciting or blocking nerve fibers selectively with respect to fiber diameter, location within a nerve or nerve bundle, or within a fascicle are described in various references. For example, myelinated fibers appear to be more susceptible to blocking by cold than are unmyelinated fibers, while myelinated fibers of different sizes may show differential sensitivity to cold block, depending at least in part on the dimensions of the cooled region. Nerve fibers in different nerves or nerve bundles may also show differential sensitivity to cold block. See, for example, U.S. Pat. Nos. 6,364,899 and 6,761,715; W. W. Douglas and J. L. Malcolm, “The effect of localized cooling on conduction in cat nerves,” J. Physiol. 1955; 130;53-71; and D. R. Franz and A. Iggo, “Conduction Failure in Myelinated and Non-Myelinated Axons at Low Temperature,” J. Physiol. (1968), 199, pp. 319-345; all of which are incorporated herein by reference in their entirety.

Alternatively, or in addition, the subset of nerve fibers in the peripheral neural structure of the subject may include nerve fibers including a selected molecular feature (as indicated at 962). Selective blocking of nerve fibers having particular molecular features has been described in Binshtok, A. M.; Bean, B. P. and Woolf, C. J.; “Inhibition of nociceptors by TRPV1-mediated entry of impermeant sodium channel blockers”; Nature, Vol. 449, 2007; pp. 607-611; doi:10.1038/nature06191 and McCleskey, E. M. “A local route to pain relief”; Nature; Vol. 449; 2007; pp. 545-546, which are incorporated herein by reference. Responsiveness of nerve fibers having selected molecular features to thermal blocking stimuli may be modulated, for example, by materials targeted to nerve fibers having the molecular feature. A variety of molecular markers for specific types of nerve fibers are known. For example, neurofilament (NF) is a highly specific marker for Myelinated nerve fibers; substance P and calcitonin gene-related protein (CGRP) are markers for sensory nerve fibers (both A and c-type); Acetylcholine (Ach) is a marker for cholinergic nerve fibers, which may be sympathetic pre-ganglionic fibers or parasympathetic pre-ganglionic or post-ganglionic fibers; tyrosine hydroxylase (TH) is specific for adrenergic nerve fibers (sympathetic postganglionic neurons). For example, see Tokushige, N.; Markham, R.; Russell, P. and Fraser, I. S.; “Nerve fibres in peritoneal endometriosis”; Human Reproduction; 2006; Vol. 21; No. 11; pp. 3001-3007, which is incorporated herein by reference in its entirety. Cyclin dependent kinase 5 (Cdk5) is expressed in nociceptive fibers (Pareek, T. K.; Keller, J.; Kesavapany, S.; Pant, H. C.; Iadarola, M. J.; Brady, R. O.; and Kulkami, A. B.; “Cyclin-dependent kinase 5 activity regulates pain signaling”; PNAS; Jan. 17, 2006; Vol. 103, No. 3; pp. 791-796), incorporated herein by reference in its entirety. Similarly, capsaicin receptor (vanilloid receptor type 1 (VR1) and variants thereof, e.g. vanilloid receptor homologue (VRL1) are expressed in A and C fiber sensory neurons, as described in Ma, Q.-P.; “Vanilloid receptor homologue, VRLI, is expressed by both A- and C-fiber sensory neurons”; Neuro Report; Vol. 12, No. 17; 4 Dec. 2001; pp. 3693, which is incorporated herein by reference in its entirety.

In some embodiments of a neural modulation system, a blocking stimulus source may be configured to produce substantially complete blockage of conduction in the peripheral neural structure of the subject responsive to the blocking stimulus control signal. In other embodiments, a blocking stimulus source may be configured to produce blockage of a subset of nerve fibers in the peripheral neural structure of the subject responsive to the blocking stimulus control signal, based, for example, upon approaches as described above. The subset of nerve fibers in the peripheral neural structure of the subject may include nerve fibers within a selected diameter range, nerve fibers within a selected spatial distribution within the peripheral neural structure, or nerve fibers including a selected molecular feature.

FIGS. 20A-20D depict examples of thermal stimulus sources that may be used in neural modulation systems as described and depicted generally herein. A blocking stimulus source may include various components capable of generating thermal stimuli, having intensity and spatial and temporal characteristics sufficient to block conduction in a nearby peripheral neural structure. FIG. 20A depicts an implantable thermal blocking stimulus source 1000 including Peltier devices 1002 and 1004 within a thermally insulating cuff 1006. Peltier device 1002 and 1004 are oriented so that heat is removed from nerve 1008, and heat is released on the exterior of cuff 1006. Heat may be dissipated by thermal radiators 1010 and 1012 on the exterior of cuff 1006. Cuff 1006 is configured to be implanted within the body of a subject, and to fit around a nerve 1008 in which conduction is to be blocked. As is known to those of skill in the art, cuff 1006 may include a slit or other opening that permits that cuff to fit around the nerve. In order to produce a conduction block, current is applied to the Peltier devices from a current source, via leads 1014 and 1016. The current source may be fully implantable. Alternatively, current may be supplied by via a wireless transcutaneous link (e.g., as described in U.S. Pat. No. 7,236,822, which is incorporated herein by reference in its entirety).

FIG. 20B depicts a thermal blocking stimulus source 1020 including Peltier device 1022 and laser diode 1024 within a thermally insulating cuff 1026. Peltier device 1022 is configured to produce cooling of nerve 1028. FIG. 20B is an example of a blocking stimulus source that includes a primary blocking stimulus source (Peltier device 1022) configured to produce a primary thermal blocking stimulus component and a secondary blocking stimulus source (laser diode 1024) configured to produce a secondary thermal blocking stimulus component. As discussed elsewhere herein, the primary thermal blocking stimulus component and the secondary thermal blocking stimulus component may act together to reversibly block conduction in the peripheral neural structure. Leads 1026 and 1028 and leads 1030 and 1032 may connect Peltier device 1022 and connect laser diode 1024, respectively, to appropriately configured driving signals, i.e. a primary blocking stimulus control signal for driving production of the primary thermal blocking stimulus component and a secondary blocking stimulus control signal for driving production of the secondary thermal blocking stimulus component. Peltier device 1022 may produce the primary thermal stimulus component and laser diode 1024 may produce the secondary thermal stimulus component.

FIG. 20C illustrates in schematic form a fluid heat transfer device 1034 that may be used for cooling a peripheral neural structure 1035. Fluid heat transfer device 1034 includes cooler 1036, pump 1037, and fluid channel 1038. Coolant fluid 1039 is pumped through fluid channel 1038 by pump 1037. Coolant fluid 1039 cools (removes heat from) peripheral neural structure 1035 and heat is removed from coolant fluid 1039 by cooler 1036. Cooler 1036 may remove heat from coolant fluid by evaporation, convection, radiation or by other cooling mechanisms, as are known to those of skill in the art.

Various configurations and combinations of devices/structures for producing heating and cooling may be used to produce conduction block by the approaches described herein, and the invention is not limited to any particular type/configuration of thermal blocking stimulus sources. It will be appreciated that in order to generate a thermal stimulus to produce either blocking or excitation, a heating or cooling source will typically be connected (via a wired or wireless connection) to an electrical current or voltage source. Accordingly, the term “blocking stimulus source”, as used herein, is considered to include at least one or more heating or cooling source(s), and may also include one or more source of electrical voltage or current to enable production of a thermal stimulus with the heating or cooling source(s).

Methods of neural modulation as described herein may be implemented with a neural modulation system 1050 as illustrated generally in FIG. 21, which depicts a variation of the system shown in FIG. 3. Basic components of neural modulation system 1050 include a signal input structure 1052, sensor 1054, and signal processing portion 1056. Signal input structure 1052 may be operatively connected to sensor 1054 and configured to receive a signal indicative of an activity state of at least a portion of a body of a subject 1055 innervated by a peripheral neural structure. Signal input structure 1052, and other signal input structures described elsewhere herein, may be of various types configured to accept or receive signals of various types. Such signal input structures are known to those of skill in the art, and may include, but are not limited to, analog or digital inputs capable of accepting or receiving electrical, optical, acoustic, electromagnetic, or other types of signals. Signals may be accepted or received at a signal input structure through direct physical contact (e.g., an electrical contact), or by reception of a signal transmitted through or across a medium (e.g., via an inductive, optical, or electromagnetic link). Sensor 1054 may be operatively connected to the signal input structure 1052 and configured to generate a signal indicative of an activity state of a portion of the body of the subject 1055 innervated by the peripheral neural structure responsive to an activity of the portion of the body 1055. Signal processing portion 1056 may be configured to distinguish a first activity state at least partially based on the signal received by the signal input structure 1052, and to generate a blocking stimulus control signal 1058 for driving production of a blocking stimulus 1060 by blocking stimulus source 1064.

FIG. 21 depicts in schematic form an embodiment of a neural modulation system 1050, in which signal processing portion 1056 and signal input structure 1052 are packaged together in package 1066 and sensor 1054, and blocking stimulus source 1064 is packaged separately. In some embodiments, blocking stimulus source 1064 or portion thereof may be located outside the body of the subject, and the blocking stimulus may pass through the skin and underlying tissue to reach the neural structure that is to be blocked. In other embodiments, a blocking stimulus source may be positioned within the body of the subject, either permanently or temporarily. Suitable positioning of the blocking stimulus source will depend upon the type of blocking stimulus source being used and the type and location of the neural structure to be blocked.

Neural modulation system 1050 may optionally include override signal input structure 1070, as indicated by the dashed box in FIG. 21. Override signal input structure 1070 may be configured to receive a signal indicative of a condition of the body of the subject, and signal processing portion 1056 may be configured to override generation of the blocking stimulus control signal 1058 responsive to a signal indicative of an override condition of the body of the subject on override signal input structure 1070. Alternatively, override signal input structure 1070 may be configured to receive a signal indicative of a condition external to the body of the subject, and signal processing portion 1056 may be configured to override generation of the blocking stimulus control signal responsive to a signal indicative of an override condition external to the body of the subject on the override signal input. As a further alternative, or in addition, override signal input structure 1070 may be configured to receive a signal from a user input device, and the signal processing portion may be configured to override generation of the blocking stimulus control signal responsive to a signal indicative of a user override request on the override signal input. The override signal may indicate that it is no longer desirable to apply the blocking stimulus, for reasons of safety, comfort, or convenience, for example, and may be indicative of a condition of the body of the subject, or of a condition external to the body of the subject (e.g., in the environment of the subject). If the override signal is detected from a user input device, it may be the same user input device used in normal operation of the system, and the override signal input structure may be the same as the signal input structure that normally receives input from a user input device.

Sensor 1054 as depicted generally in FIG. 21 (and, in addition, sensors used in other embodiments depicted and/or described herein) may include any of a variety of different types of sensors, including, but not limited to, pressure sensors, force sensors, chemical sensors (including but not limited to sensors capable of sensing pH, gas, ions, proteins, or biomolecules), temperature sensors, electrical sensors (for sensing current, potential, charge, resistance, resistivity, capacitance, or other electrical parameters), magnetic sensors, optical sensors, motion sensors, etc. A single sensor or multiple sensors, of the same or multiple different types, may be used.

The signal processing portion 1056, as depicted in FIG. 21, may be configured to determine the onset of the first activity state and generate the blocking stimulus control signal for driving production of a thermal blocking stimulus configured to reversibly block conduction in the peripheral neural structure of the subject at least intermittently responsive to detecting the onset of a first activity state in the subject. In some cases, the signal processing portion may be configured to generate the blocking stimulus control signal for driving production of a thermal blocking stimulus configured to reversibly block conduction in the peripheral neural structure of the subject substantially immediately upon detecting the onset of the first activity state in the subject. In other cases, the signal processing portion may be configured to generate the blocking stimulus control signal for driving production of a thermal blocking stimulus configured to reversibly block conduction in the peripheral neural structure of the subject at a delay interval after detecting the onset of the first activity state in the subject. The signal processing portion may be configured to initiate a release period during which no blocking stimulus control signal is generated after an interval determined relative to the onset of generation of the blocking stimulus control signal.

In some cases, the signal processing portion may be configured to determine the onset of the second activity state in the subject and initiate a release period during which no blocking stimulus control signal is generated responsive to detecting the second activity state in the subject. The signal processing portion may be configured to initiate the release period substantially immediately upon detection of the onset of the second activity state in the subject, or to initiate the release period at a delay interval after detection of the onset of the second activity state in the subject.

Components of neural modulation systems of the type described herein may be packaged in various manners. In some cases, all components of a system may be packaged together. Such a package may be designed for use outside the body, or designed for use inside the body in an implantable system. However, in many cases it may be desirable to package certain components of the system separately. Communication between system components may be wireless, e.g. as described in U.S. Pat. No. 6,208,894, which is incorporated herein by reference in its entirety. The system may include the capability for remote programming, interrogation, or telemetry, for example as described in U.S. Pat. No. 7,263,405, which is incorporated herein by reference in its entirety.

FIG. 22 depicts an example of a neural modulation system 1100 in which a sensor (motion sensor 1102) and blocking stimulus source are packaged with signal processing portion 1106 in package 1108. Motion sensor 1102 provides an input to signal processing portion 1106 via signal input structure 1110. Signal processing portion 1106 generates blocking stimulus control signal 1112 which drives production of blocking stimulus 1114 by thermal blocking stimulus source 1104. Package 1108 may be adapted to be positioned external to the body of subject 1055, and thermal blocking stimulus 1114 may pass through body tissues to reach peripheral neural structure 1062. Thermal blocking stimulus source 1104 may include, for example, a thermoelectric, optical or acoustic source configured to deliver a thermal stimulus to the body of the subject sufficient to produce blocking of a nerve, as described elsewhere herein. Package 1108 may be configured to secured to a limb (e.g., with a strap or elastic band) over a peripheral neural structure 1062, so that the thermal blocking stimulus may be delivered to the peripheral neural structure. Generation of blocking stimulus control signal 1112 by signal processing portion 1106 may be responsive to a signal from motion sensor 1102, such that a blocking stimulus may be delivered to the peripheral neural structure when the limb is not in motion, for example. The peripheral neural structure may be, for example, a sensory nerve, and blockage of neural activity therein may, for example, reduce or limit pain or inflammation, e.g. of arthritis, peripheral vascular disease, etc. In related embodiments, sensor 1102 may be any of various types of sensors, as described elsewhere herein.

FIG. 23 depicts an example of a neural modulation system 1150 in which an implanted sensor and implanted blocking stimulus source are used. In this example, the implanted sensor may be sensing electrode 1152, and the blocking stimulus source may be Peltier cooler 1154. Peltier cooler 1154 may, for example, be of the type described in U.S. Published Patent Application 20050138934, which is incorporated herein by reference in its entirety. In other implanted devices, other cooling devices/mechanisms may be used, including but not limited to fluid heat transfer or evaporative devices, e.g. as described in U.S. Pat. No. 6,762,715, which is incorporated herein by reference in its entirety. Sensing electrode 1152 and Peltier cooler 1154 may be implanted within the body of subject 1055, such that sensing electrode 1152 may sense neural or muscular activity representative of activity of at least a portion of the body of the subject, and Peltier cooler 1154 may deliver blocking stimulus 1156 to a peripheral neural structure, peripheral nerve 1062. As used herein, “implanted” means located or positioned, either temporarily or permanently, within the body of the subject. Signal processing portion 1158 may be packaged separately, e.g. in package 1160. Sensing electrode 1152 may provide an input to signal processing portion 1158 via signal input structure 1162. Signal processing portion 1158 may generate blocking stimulus control signal 1164 for driving production of blocking stimulus 1156 by Peltier cooler 1154. Package 1160 may be implanted within the body of subject 1055, or located external to body of subject 1055. In either case, signals may be transmitted between signal processing portion 1158 and sensing electrode 1152 and Peltier cooler 1154 via a wire or cable, optical ink, acoustic link, radiofrequency or other electromagnetic link, or other wireless communication link, as is known to those of skill in the art. As discussed in connection with FIG. 24, blockage of neural activity may reduce or limit pain or inflammation. In one application, for example, sensing electrode 1152 and Peltier cooler 1154 may be implanted on a sensory nerve innervating a limb, appendage, or joint (for example, a knee) that has suffered injury and/or damage, with the goal of limiting the progression of arthritis that would otherwise be associated with the injury or damage.

FIG. 24 depicts in further detail an example of a system 1200 in which components are packaged so that some can be used locally (e.g. implanted in the body or positioned on or near the body surface) while others are used remotely, which in this context may be in a separate package located relatively close by (i.e. in, on or near the body), or at a distant location such as across a room, in a separate room, or in a separate building). System 1200 includes local portion 1202 and remote portion 1204. Local portion 1202 may be implanted in the body of a subject or positioned on or near the body surface, while remote portion 1204 may be located remotely from local portion 1202. Local portion 1202 may include sensor 1206 and blocking stimulus source 1208. Local portion 1202 may also include local circuitry portion 1210 and receiver/transmitter 1212. A corresponding receiver/transmitter 1212 in remote portion 1204 permits the transmission of data and instructions between local portion 1202 and remote portion 1204. In some embodiments, power may also be transmitted between remote portion 1204 and local portion 1202. Alternatively, or in addition, one or both of local portion 1202 and remote portion 1204 may include a power source (e.g., a battery or other power source as known to those of skill in the art). Remote portion 1204 may include remote circuitry 1216, which may include signal processing portion 1218. The signal processing portion of the system may include only signal processing portion 1218 in remote portion 1204, or it may include both signal processing portion 1218 in remote portion 1204 and signal processing portion 1220 in local portion 1202. Alternatively, in some embodiments, the signal processing portion may include signal processing portion 1220 in local portion 1202 and remote circuitry 1216 may be devoted to other functions.

Components packaged separately may be operatively connected to other components by cables, a wireless link (which may be optical, electromagnetic, acoustic, etc.). Separately packaged components may be suited for use outside or inside the body. In some embodiments, some components may be positioned inside the body while other are positioned outside the body during use. In some embodiments, the signal processing portion may be configured to perform encryption of signals transmitted to separately packaged and/or remote components or device portion, e.g. a blocking stimulus control signal. Similarly, the signal processing portion may be configured to perform decryption of signals received from, e.g., a user input device, via a signal input structure or override signal input structure. Encryption/decryption may be performed by standard methods as known to those of skill in the art, for example, as used in computers, networks, mobile telephones, wireless microphones, wireless intercom systems, Bluetooth devices, and so forth. Encryption/decryption may be used in order to provide secure transmission of information, for example for protecting privacy of personal information and/or for avoiding interference between multiple devices used in the same area.

In some embodiments, a user input device may be used in place of (or in addition to) a sensor in order to provide indication of an activity or use state of all or a portion of the body of the subject. Such a system is depicted in schematic form in FIG. 25. As shown in FIG. 25, neural modulation system 1250 may include a signal input structure 1252 configured to receive a signal 1254 indicative of an activity state of at least a portion of a body of a subject 1256 innervated by a peripheral neural structure 1258; a user input device (switch 1260) operatively connected to the signal input structure 1252 and configured to generate a signal 1254 responsive to a user input indicative of an activity state of at least a portion of a subject 1256 innervated by the peripheral neural structure 1258. For example, switch 1260 may be set to the “on” setting when the subject is entering a first activity state, and set to the “off” setting when the subject is entering a second activity state. Neural modulation system 1250 also includes signal processing portion 1262 configured to distinguish a first activity state of the at least a portion of the body of the subject 1256 innervated by the peripheral neural structure 1258 from a second activity state of the at least a portion of the body of the subject 1256 innervated by the peripheral neural structure 1258 from the signal 1254 received at the signal input structure 1252 (e.g., by detecting the “on” or “off” setting of switch 1260); and generate a blocking stimulus control signal 1264 for driving production of a blocking stimulus 1266 configured to reversibly block conduction in the peripheral neural structure 1258 of the body of subject 1256 during at least a portion of the first activity state. Blocking stimulus 1266 is produced by a blocking stimulus source 1270 responsive to blocking stimulus control signal 1264.

A user of the system depicted in FIG. 25 (the subject or another party, such as a medical care-giver or assistant) may use user input device (e.g., switch 1260) to indicate that the subject is currently resting or inactive (e.g., sitting in a chair or lying in bed) or about to begin a period of rest or inactivity, e.g., by changing the setting of switch, as described above. Similarly, a user of the system may also use the user input device to indicate the end of a period of rest or inactivity. The user input device may include various types of user input devices, as are known to those of skill in the art. For example, the user input device may include one or more of the following: a voice-activated or other sound-activated input device, e.g. a microphone, a user-activated switch or knob, a keyboard, a mouse or other pointing device, a touch-screen or other user activated input devices.

The foregoing are examples, and various other devices that allow the subject or other user to signal a change (or expected change) in activity state may be used in practice.

As discussed in connection with systems in which sensors are used to provide indication of an activity or use state of all or a portion of the body of the subject, the various components of the system may be packaged together or separately, located locally or remotely, inside or outside the body of the subject, as depicted in FIGS. 21-26. For example, FIG. 25 shows an example of a system in which switch 1260 is packaged separately from the signal processing portion 1262 and is located outside of the body of subject 1256, while blocking stimulus source 1270 is packaged with signal processing portion 1262. Signal processing portion 1262 and blocking stimulus source 1270 may be in a package configured to be placed against the subject's body as the subject rests, while switch 1260 may be connected to signal processing portion 1262 with a cable, for example (or, alternatively, a wireless connections such as an optical or RF connection). The subject may toggle switch 1260 to indicate the beginning or end of a rest period during which the blocking stimulus is to be delivered. Blocking stimulus source 1270 may be configured to generate a thermal stimulus sufficient to block conduction in peripheral neural structure. Peripheral neural structure 1258 may be blocked with the goal of producing a particular beneficial effect, such as to limit the progression of an inflammatory process (e.g. in diabetes, arthritis, vascular disease).

FIG. 26 depicts a further example of a system 1300 in which user input device 1302 is packaged separately from signal processing portion 1304, providing signal 1306 to signal input structure 1308. Signal processing portion 1304 generates blocking stimulus control signal 1310, which is provided (e.g., transmitted) to blocking stimulus source 1312, which is implanted within the body of subject 1256. As discussed previously, blocking stimulus source 1312 generates blocking stimulus 1314 for blocking conduction in peripheral neural structure 1258 in body of subject 1256. Other arrangements of system components are possible, and systems as described generally herein are not limited to the specific arrangements of components depicted in the figures.

A schematic diagram showing components and operation of a signal processing portion 1350 of a neural modulation system 1352 is shown in FIG. 27. The functional relationship of signal processing portion 1350 to other components of neural modulation system 1352 is also shown. As noted previously, signal processing portion 1350 and other system components may be powered by a single power source, as shown in FIG. 26 as power source 1354; or multiple power sources. Signal processing portion 1350 may receive as input signals from one or more sensors 1356 and/or one or more user input devices 1358 via signal input structure 1359, and optionally, a signal from override signal input structure 1360. Signal processing portion 1350 may generate as output blocking stimulus control signal 1361 for driving blocking stimulus source 1362 to produce a blocking stimulus.

Signal processing portion 1350 may include electrical circuitry 1364 for performing signal processing functions including but not limited to amplification, filtering, signal averaging, thresholding, variable-changing, waveform analysis, variable (e.g., time- or spatial-frequency) domain transformation, convolution, cross-spectral analysis, feature or pattern recognition or extraction, processing performed relative to data-stored-in-memory, etc., or a combination or concatenation of any or all of these, as is known to those of skill in the art of signal processing, whether such operations may be done in software, firmware or hardware or combinations of these. Electrical circuitry 1364 may also be configured to generate blocking stimulus control signal 1361 for driving blocking stimulus source 1362. In some embodiments, blocking stimulus control signal 1361 may include a primary blocking stimulus control signal for driving primary blocking stimulus source 1362, and electrical circuitry 1364 may also be configured to generate secondary blocking stimulus control signal 1386 for driving secondary blocking stimulus source 1388. Detection of the onset or end of an activity state is not limited to threshold-based determinations, but may include various other types of signal processing as known to those of skill in the art; for example analysis of the trend of the signal may be used to predict the onset of an activity state. Accordingly, operations performed in response to detection or determination of the onset of a particular activity state may in some cases be based upon the predicted onset of an activity state, and may occur before, after, or simultaneously with the predicted onset of an activity state. Electrical circuitry or other components of a signal processing portion may accordingly be configured to generate a blocking stimulus or to initiate a release period prior to, simultaneously with, or subsequently to the predicted the onset of an activity state in the subject.

The blocking stimulus may be applied with a repetitive or cyclical application pattern according to a detected signal indicative of at least one activity state in the subject and/or according to a pre-set schedule. Signal processing portion 1350 may include at least one signal bearing medium 1366 that may contain blocking stimulus pattern 1368, which specifies the configuration (e.g. waveform and timing of application) of a blocking stimulus. Signal bearing medium 1366 may also include blocking stimulus parameters 1370 related to generating blocking stimulus control signal 1360 according to a detected signal from sensor 1356 or user input 1358. Stimulus parameters 1370 may include constants and/or variables to be used in calculations of blocking stimulus control signal 1361 as a function of the detected signal. Signal bearing medium 1366 may include instructions 1372, which may relate to one or more of receiving or acquiring signals on signal input structure 1359, processing the signals, generating blocking stimulus control signal 1360, storing data (e.g. signals or parameters representing some or all of sensor or user input, blocking stimulus control signal, etc.) in data storage location 1374, and instructions related to transmitting and/or receiving data or instructions via transmitter/receiver circuitry 1376. Electrical circuitry 1364 and signal bearing medium 1366 may optionally include instructions, patterns, and/or parameters for use in generating release stimulus control signal 1380 for producing discontinuation of generation of a blocking stimulus by blocking stimulus source 1362, and instruction, patterns, and/or parameters for use in generating reversing stimulus control signal 1382 for driving generation of a reversing stimulus by reversing stimulus source 1384.

In a general sense, those skilled in the art will recognize that the various aspects described herein that can be implemented, individually and/or collectively, by a wide range of hardware, software, firmware, or any combination thereof can be viewed as being composed of various types of “electrical circuitry.” Consequently, as used herein “electrical circuitry” includes, but is not limited to, electrical circuitry having at least one discrete electrical circuit, electrical circuitry having at least one integrated circuit, electrical circuitry having at least one application specific integrated circuit, electrical circuitry forming a general purpose computing device configured by a computer program (e.g., a general purpose computer configured by a computer program that at least partially carries out processes and/or devices described herein, or a microprocessor configured by a computer program that at least partially carries out processes and/or devices described herein), electrical circuitry forming a memory device (e.g., forms of random access memory), and/or electrical circuitry forming a communications device (e.g., a modem, communications switch, or optical-electrical equipment). Those having skill in the art will recognize that the subject matter described herein may be implemented in an analog or digital fashion or some combination thereof.

Operation of neural modulation devices as described herein may be performed under the control of hardware (e.g. analog or digital electronic circuitry). Circuitry for switching, signal generation, sensing, timing control etc. is well known and may be constructed by those of skill in the art of electronics. In some embodiments, control of neural modulation devices as described herein may be performed under microprocessor control. Instructions to be executed by a microprocessor may be stored in hardware, firmware, or software (e.g. as an ASIC, instructions burned into an EEPROM, instructions stored in various types of memory devices/structures) on various types of signal-bearing media. Instructions for controlling neural modulation devices as described herein may be used, for example to implement methods as outlined, e.g. in FIGS. 4, 6 and 13-18. Instructions carried on a signal bearing medium may form a permanent or temporary component of a system including additional device components. Signal bearing media used, e.g. as depicted in FIG. 27, may include both instructions for controlling neural modulation device, and also stored data or parameters. Data, parameters, and instructions may be stored on more than one types of media during the practice of the invention (e.g., partially in device memory, partially on a removable medium, etc.).

A signal processing portion used in various embodiments as disclosed herein may be configured to perform the various described steps by appropriately configured analog or digital hardware, by instructions encoded in software or firmware, or combinations thereof, or by other methods as are known to those of skill in the art. Those having skill in the art will recognize that the state of the art has progressed to the point where there is little distinction left between hardware and software implementations of aspects of systems; the use of hardware or software is generally (but not always, in that in certain contexts the choice between hardware and software can become significant) a design choice representing cost vs. efficiency tradeoffs. Those having skill in the art will appreciate that there are various vehicles by which processes and/or systems and/or other technologies described herein can be effected (e.g., hardware, software, and/or firmware), and that the preferred vehicle will vary with the context in which the processes and/or systems and/or other technologies are deployed. For example, if an implementer determines that speed and accuracy are paramount, the implementer may opt for a mainly hardware and/or firmware vehicle; alternatively, if flexibility is paramount, the implementer may opt for a mainly software implementation; or, yet again alternatively, the implementer may opt for some combination of hardware, software, and/or firmware. Hence, there are several possible vehicles by which the processes and/or devices and/or other technologies described herein may be effected, none of which is inherently superior to the other in that any vehicle to be utilized is a choice dependent upon the context in which the vehicle will be deployed and the specific concerns (e.g., speed, flexibility, or predictability) of the implementer, any of which may vary.

The foregoing detailed description has set forth various embodiments of the devices and/or processes via the use of block diagrams, flowcharts, and/or examples. Insofar as such block diagrams, flowcharts, and/or examples contain one or more functions and/or operations, it will be understood by those within the art that each function and/or operation within such block diagrams, flowcharts, or examples can be implemented, individually and/or collectively, by a wide range of hardware, software, firmware, or virtually any combination thereof. In one embodiment, several portions of the subject matter described herein may be implemented via Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs), digital signal processors (DSPs), or other integrated formats. However, those skilled in the art will recognize that some aspects of the embodiments disclosed herein, in whole or in part, can be equivalently implemented in integrated circuits, as one or more computer programs running on one or more computers (e.g., as one or more programs running on one or more computer systems), as one or more programs running on one or more processors (e.g., as one or more programs running on one or more microprocessors), as firmware, or as virtually any combination thereof, and that designing the circuitry and/or writing the code for the software and or firmware would be well within the skill of one of skill in the art in light of this disclosure. In addition, those skilled in the art will appreciate that the mechanisms of the subject matter described herein are capable of being distributed as a program product in a variety of forms, and that an illustrative embodiment of the subject matter described herein applies regardless of the particular type of signal bearing medium used to actually carry out the distribution. Examples of a signal bearing medium include, but are not limited to, the following: a recordable type medium such as a floppy disk, a hard disk drive, a Compact Disc (CD), a Digital Video Disk (DVD), a digital tape, a computer memory, etc.; and a transmission type medium such as a digital and/or an analog communication medium (e.g., a fiber optic cable, a waveguide, a wired communications link, a wireless communication link, etc.).

One skilled in the art will recognize that the herein described components (e.g., steps), devices, and objects and the discussion accompanying them are used as examples for the sake of conceptual clarity and that various configuration modifications are within the skill of those in the art. Consequently, as used herein, the specific exemplars set forth and the accompanying discussion are intended to be representative of their more general classes. In general, use of any specific exemplar herein is also intended to be representative of its class, and the non-inclusion of such specific components (e.g., steps), devices, and objects herein should not be taken as indicating that limitation is desired.

With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations are not expressly set forth herein for sake of clarity.

The herein described subject matter sometimes illustrates different components contained within, or connected with, different other components. It is to be understood that such depicted architectures are merely exemplary, and that in fact many other architectures can be implemented which achieve the same functionality. In a conceptual sense, any arrangement of components to achieve the same functionality is effectively “associated” such that the desired functionality is achieved. Hence, any two components herein combined to achieve a particular functionality can be seen as “associated with” each other such that the desired functionality is achieved, irrespective of architectures or intermedial components. Likewise, any two components so associated can also be viewed as being “operably connected”, or “operably coupled”, to each other to achieve the desired functionality, and any two components capable of being so associated can also be viewed as being “operably couplable”, to each other to achieve the desired functionality. Specific examples of operably couplable include but are not limited to physically mateable and/or physically interacting components and/or wirelessly interactable and/or wirelessly interacting components and/or logically interacting and/or logically interactable components.

In some instances, one or more components may be referred to herein as “configured to.” Those skilled in the art will recognize that “configured to” can generally encompass active-state components and/or inactive-state components and/or standby-state components, etc. unless context requires otherwise.

While particular aspects of the present subject matter described herein have been shown and described, it will be apparent to those skilled in the art that, based upon the teachings herein, changes and modifications may be made without departing from the subject matter described herein and its broader aspects and, therefore, the appended claims are to encompass within their scope all such changes and modifications as are within the true spirit and scope of the subject matter described herein. Furthermore, it is to be understood that the invention is defined by the appended claims. It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should typically be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations,” without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to “at least one of A, B, and C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to “at least one of A, B, or C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase “A or B” will be understood to include the possibilities of “A” or “B” or “A and B.” With respect to the appended claims, those skilled in the art will appreciate that recited operations therein may generally be performed in any order. Examples of such alternate orderings may include overlapping, interleaved, interrupted, reordered, incremental, preparatory, supplemental, simultaneous, reverse, or other variant orderings, unless context dictates otherwise. With respect to context, even terms like “responsive to,” “related to,” or other past-tense adjectives are generally not intended to exclude such variants, unless context dictates otherwise.

While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not 

1. A method of modulating neural activity comprising the steps of: producing a reversible conduction block in a peripheral neural structure of a subject with a thermal stimulus while the subject is in a first activity state; reversing the reversible conduction block in the peripheral neural structure of the subject to permit conduction in the peripheral neural structure when the subject is in a second activity state; and repeating the steps of producing a reversible conduction block in a peripheral neural structure of a subject with a thermal stimulus while the subject is in a first activity state and reversing the reversible conduction block in the peripheral neural structure of the subject to permit conduction in the peripheral neural structure when the subject is in a second activity state.
 2. The method of claim 1, wherein the overall activity of the subject is lower in the first activity state than in the second activity state.
 3. The method of claim 1, wherein a use of a body portion innervated by the peripheral neural structure by the subject is lower in the first activity state than in the second activity state. 4.-9. (canceled)
 10. The method of claim 1, wherein producing the reversible conduction block in the peripheral neural structure of the subject includes producing the reversible conduction block in a peripheral nerve of the subject. 11.-19. (canceled)
 20. The method of claim 10, wherein producing the reversible conduction block in the peripheral nerve of the subject includes producing the reversible conduction block in a vagus nerve of the subject. 21.-25. (canceled)
 26. The method of claim 25, wherein receiving an input indicative of an activity state of the subject includes receiving an input representing physiological activity of the subject. 27.-32. (canceled)
 33. The method of claim 25, wherein receiving an input indicative of an activity state of the subject includes receiving an input representative of physical activity of the subject. 34.-41. (canceled)
 42. The method of claim 25, wherein receiving an input indicative of an activity state of the subject includes receiving an input representing rest or waking state of the subject.
 43. The method of claim 1, including receiving an input indicative of a user instruction.
 44. The method of claim 43, wherein receiving an input indicative of a user instruction includes receiving a signal from a user input device. 45.-56. (canceled)
 57. The method of claim 1, wherein producing a reversible conduction block in a peripheral neural structure of a subject while the subject is in a first activity state includes producing a reversible conduction block in a peripheral neural structure of a subject with a blocking stimulus source worn on the body of the subject. 58.-60. (canceled)
 61. The method of claim 1, wherein producing a reversible conduction block in a peripheral neural structure of a subject while the subject is in a first activity state includes producing a reversible conduction block in a peripheral neural structure of a subject with a blocking stimulus source configured to be positioned beneath at least a portion of the body of the subject. 62.-64. (canceled)
 65. The method of claim 1, wherein producing a reversible conduction block in a peripheral neural structure of a subject while the subject is in a first activity state includes producing a reversible conduction block in a peripheral neural structure of a subject with a blocking stimulus source implanted within the body of the subject. 66.-82. (canceled)
 83. The method of claim 1, including reversing the reversible conduction block in the peripheral neural structure of the subject to permit conduction in the peripheral neural structure when the subject is in a second activity state by removing a blocking stimulus used to produce the reversible conduction block in the peripheral neural structure of the subject. 84.-87. (canceled)
 88. The method of claim 1, wherein producing a reversible conduction block in a peripheral neural structure of a subject with a thermal stimulus includes producing a primary thermal blocking stimulus component and producing a secondary thermal blocking stimulus component, wherein the primary thermal blocking stimulus component and the secondary thermal blocking stimulus component act together to reversibly block conduction in the peripheral neural structure.
 89. The method of claim 88, wherein the primary thermal stimulus component includes static cooling stimulus and the secondary thermal stimulus component includes a pulsed transient heating stimulus. 90.-91. (canceled)
 92. A method of modulating neural activity comprising the steps of: producing a reversible conduction block in a peripheral neural structure of a subject with a thermal stimulus while the subject is in a first activity state; reversing the reversible conduction block in the peripheral neural structure of the subject to permit conduction in the peripheral neural structure when the subject is in a second activity state by applying a reversing stimulus configured to counter the blocking stimulus used to produce the reversible conduction block in the peripheral neural structure of the subject; and repeating the steps of producing a reversible conduction block in a peripheral neural structure of a subject while the subject is in a first activity state and reversing the reversible conduction block in the peripheral neural structure of the subject to permit conduction in the peripheral neural structure when the subject is in a second activity state. 93.-102. (canceled)
 103. A method of modulating neural activity comprising the steps of: producing a reversible conduction block in a peripheral neural structure of a subject with a thermal stimulus while the subject is in a first activity state; reversing the reversible conduction block in the peripheral neural structure of the subject to permit conduction in the peripheral neural structure when the subject is in a second activity state; repeating the steps of producing a reversible conduction block in a peripheral neural structure of a subject while the subject is in a first activity state and reversing the reversible conduction block in the peripheral neural structure of the subject to permit conduction in the peripheral neural structure when the subject is in a second activity state; determining that producing the reversible conduction block in the peripheral neural structure of the subject while the subject is in a first activity state results in a desired effect in the subject; and producing a non-reversible conduction block in the peripheral neural structure of the subject. 104.-116. (canceled)
 117. The method of claim 103, wherein producing a reversible conduction block includes producing substantially complete blockage of conduction in the peripheral neural structure of the subject.
 118. A method of modulating neural activity comprising the steps of: producing a reversible conduction block of a subset of nerve fibers in a peripheral neural structure of a subject with a thermal stimulus while the subject is in a first activity state; reversing the reversible conduction block of the subset of nerve fibers in the peripheral neural structure of the subject to permit conduction in the subset of nerve fibers in the peripheral neural structure when the subject is in a second activity state; and repeating the steps of producing a reversible conduction block in the subset of nerve fibers in a peripheral neural structure of a subject while the subject is in a first activity state and reversing the reversible conduction block in the subset of nerve fibers in the peripheral neural structure of the subject to permit conduction in the subset of nerve fibers in the peripheral neural structure when the subject is in a second activity state. 119.-122. (canceled)
 123. The method of claim 1, wherein the steps of producing a reversible conduction block in a peripheral neural structure of a subject while the subject is in a first activity state and reversing the reversible conduction block in the peripheral neural structure of the subject to permit conduction in the peripheral neural structure when the subject is in a second activity state occur over a period of time sufficient to produce a modulation of at least one of an immune response or an inflammatory response in a region innervated by the peripheral neural structure.
 124. The method of claim 1, wherein producing the reversible conduction block in the peripheral neural structure of the subject includes producing the reversible conduction block in at least one of a sensory-motor nerve or an autonomic nerve of the subject.
 125. The method of claim 10, wherein producing the reversible conduction block in the peripheral nerve of the subject includes producing the reversible conduction block in at least one of a radial nerve, a median nerve, an ulnar nerve, a femoral nerve, an obturator nerve, a sciatic nerve, a popliteal nerve, a tibial nerve, or a peroneal nerve of the subject.
 126. The method of claim 1, wherein producing the reversible conduction block in the peripheral neural structure of the subject includes producing the reversible conduction block in at least one of a spinal root, a geniculate ganglion, an autonomic ganglion, or a nerve plexus of the subject.
 127. The method of claim 26, wherein receiving an input representing physiological activity of the subject includes receiving an input representing at least one of heart rate, respiration, brain activity, peripheral neural activity, muscle activity, or body temperature of the subject.
 128. The method of claim 33, wherein receiving an input representative of physical activity of the subject includes receiving an input representative of at least one of motion of the subject, body position of the subject or posture of the subject.
 129. The method of claim 33, wherein receiving an input representative of physical activity of the subject includes receiving an input from at least one of a pressure sensor, a force sensor, an accelerometer, a gyro, a switch, or a piezoelectric device.
 130. The method of claim 44, wherein receiving a signal from a user input device includes receiving a signal from at least one of a sound-activated input device, a user-activated switch, a pointing device, a touch screen, a keyboard or a user-controlled intermediate device.
 131. The method of claim 43, wherein receiving an input indicative of a user instruction includes receiving an input indicative of an instruction to modify at least one of the definition of the first activity state or the definition of the second activity state.
 132. The method of claim 57, wherein producing a reversible conduction block in a peripheral neural structure of a subject while the subject is in a first activity state includes producing a reversible conduction block in a peripheral neural structure of a subject with a blocking stimulus source located in or on at least one of a wrap adapted to be positioned around at least a portion of the body of the subject, a bracelet, anklet, or cuff configured to be worn on a limb of the subject, or a collar or necklace configured to be worn on a neck of the subject.
 133. The method of claim 61, wherein producing a reversible conduction block in a peripheral neural structure of a subject while the subject is in a first activity state includes producing a reversible conduction block in a peripheral neural structure of a subject with a blocking stimulus source located in or on at least one of a chair, a bed, a pad or cushion.
 134. The method of claim 1, wherein producing a reversible conduction block includes at least one of cooling or heating at least a portion of the peripheral neural structure.
 135. The method of claim 1, wherein producing a reversible conduction block includes at least one of applying a magnetic field, applying a pulsed magnetic field, applying a thermal stimulus, applying a time-varying electrical field, delivering electromagnetic energy, delivering about 1 GHz to about 30 GHz electromagnetic energy, delivering optical spectrum photons, delivering acoustic energy, or delivering at least one chemical agent to at least a portion of the peripheral neural structure.
 136. The method of claim 1, including at least one of storing information regarding an activity state of the subject, storing information regarding producing the reversible conduction block, transmitting information regarding an activity state of the subject, or transmitting information regarding producing the reversible conduction block.
 137. The method of claim 1, wherein the thermal stimulus includes at least one of a time-varying thermal stimulus or a spatially-varying thermal stimulus.
 138. The method of claim 92, wherein applying a reversing stimulus to counter the blocking stimulus used to produce the reversible conduction block in the peripheral neural structure of the subject includes at least one of applying heat to at least a portion of the peripheral neural structure or removing heat from at least a portion of the peripheral neural structure.
 139. The method of claim 92, wherein applying a reversing stimulus to counter the blocking stimulus used to produce the reversible conduction block in the peripheral neural structure of the subject includes at least one of applying an electric field, applying a pulsed electric field, applying a magnetic field, applying a pulsed magnetic field, applying electromagnetic energy, applying optical photons, applying acoustic energy, or applying at least one chemical agent to at least a portion of the peripheral neural structure.
 140. The method of claim 103, including: producing a non-reversible conduction block by at least one of applying heat to at least a portion of the peripheral neural structure of the subject, removing heat from at least a portion of the peripheral neural structure of the subject, applying an electrical current to at least a portion of the peripheral neural structure of the subject, delivering acoustic energy to at least a portion of the peripheral neural structure of the subject, delivering photons to at least a portion of the peripheral neural structure of the subject, delivering a chemical agent to at least a portion of the peripheral neural structure of the subject, delivering capsaicin to at least a portion of the peripheral neural structure of the subject, or surgical transection of at least a portion of the peripheral neural structure of the subject.
 141. The method of claim 118, wherein the subset of nerve fibers in the peripheral neural structure of the subject includes at least one of nerve fibers within a selected diameter range, nerve fibers within a selected spatial distribution within the peripheral neural structure, nerve fibers within selected fascicles within the peripheral neural structure or nerve fibers including a selected molecular feature. 